After reading it twice I found this article to answer a lot of questions on both formats {DVD -+ R/RW} and why +R/RW is on paper the better format. I'm going to chop up the article a bit. but will leave the link for those who wish to read the whole thing.
http://www.wuliweb.com/itiger/itview-connectedwindow.asp?barcodeid=1201551Read more

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Designed for professional content developers and software producers, today's Authoring DVDs' primary use is to create check discs and master discs that will be replicated as DVD titles. General DVD media is intended for business and consumer applications, such as data backups, archiving, and personal video. While "General Use" DVD is a term devised specifically by Pioneer to distinguish its "Authoring" and non-authoring DVD-R media, here, we'll use "General Use" more broadly to describe the multiple write-once and rewritable formats competing for the "general" business/consumer market. All discs under our General Use umbrella (including Pioneer's DVD-R and -RW, plus the DVD+R and DVD+RW formats) prohibit users from writing the Disc Description Protocol data required by replicators for mastering into the lead-in area of the disc, which makes them ill-suited to premastering/mastering. General Use media is also designed to make it physically impossible to copy CSS-encrypted entertainment titles bit-for-bit. Authoring and General media are also write-incompatible, due to differences in write-laser wavelength: Authoring uses a 635nm laser (available in Pioneer's DVR-S201 recorder), while General uses 650nm (available in Pioneer's A03 and A04 drives). In other words, while the discs should theoretically be readable in most of the same players and drives (remember, DVD specs specify media characteristics, not player characteristics), you can only write them in recorders designed specifically for that media type.

Inside of the General DVD media scope exist two methods for storing data, write-once and rewritable. Current write-once formats include DVD-R and DVD+R. They work under similar principles to CD-R technology only with different dyes and smaller geometries. A blank disc contains a layer of dye that is burned, or written, by the laser. The technique is permanent; therefore, data cannot be erased, modified, or written over. Rewritable DVD formats include DVD-RAM, DVD-RW, and DVD+RW. Instead of burning dye, the laser heats a layer of phase-change alloy. The temperature level and subsequent cooling rate determine whether or not the alloy is crystalline (reflective) or amorphous (non-reflective). These processes create marks that drives read in the same way that they read the pits and lands of pressed media.

The various drives read data in two different methods: constant angular velocity (CAV) and constant linear velocity (CLV). CAV works by spinning discs at a constant rate of revolutions per minute (RPM) without regard to the location on the disc of the data being written or read. This allows for the quick random access required by computer and game write/read storage. CLV rotates discs at different RPMs, providing the constant data stream needed for applications, such as streaming video. DVD-R and DVD-RW utilize the CLV method, making them ideal for DVD-Video, but slower when used for data storage. DVD+RW and DVD-RAM are designed to use a blend of both CAV and CLV, though this blend has only been implemented to date in DVD-RAM. Allowing data to be transferred at a variable rate while the drive spins at a constant rate called Zoned CLV, DVD-RAM acts like a hard drive (though considerably slower), which gives it a clear technical edge for small-block data storage and retrieval.

THE JUGGERNAUTS
An Alliance and a Forum stand at odds in the format wars. While both organizations' respective missions focus on furthering recordable DVD technology, they don't agree on how to accomplish it.

Created in 2001, the DVD+RW Alliance (www.dvdrw.com) supports the DVD+R and DVD+RW specifications. It represents an international cadre of companies known in many cases for their CD-R/ RW acumen, including Hewlett-Packard Company, MCC/Verbatim, Philips Electronics, Ricoh Company Ltd., Sony Corporation, Yamaha Corporation, Thomson multimedia, and Dell. The DVD Forum (www.dvdforum.org), established in April 1997, has a member list about 230 strong, as well as over half of the Alliance's roster. The Forum has approved the DVD-R, DVD-RW, and DVD-RAM specifications, but not DVD+R/RW.

COMPATIBILITY
A major issue in the DVD format wars is that of compatibility: which drives will write to what discs, and which discs will play in which DVD-Video players, DVD-ROM drives, and DVD recording devices. Since DVD format specifications have been finalized at various times since the beginning of DVD recording and playback, manufacturers of drives, players, and writers have had trouble completely eliminating compatibility issues, especially with legacy drives and players. Testing and ensuring compatibility has proven a labor-intensive process, requiring testing of each media format and brand, as written in each brand of drive, with new playback devices. Combine that with the multitudes of drives and players being manufactured by many different companies, some of which support one format over the other, and problems inevitably arise. Which format truly is the most compatible with the largest number of drives and players already on the market?

Because of the process involved in recording data, write-once DVDs tend to prove compatible in a wider range of DVD playback devices than the rewritable formats. Phase-change technology simply cannot create the same level of reflectivity as the burning of dye. DVD-R and DVD+R reach a reflectivity of between 45 and 85 percent, while the rewritable formats write in the 18 to 30 percent region. A lower reflectivity means that drives must be that much more exact and compatible with the disc that they are trying to read.

In addition to its fast random access, which makes it well-suited to data storage and retrieval tasks, DVD-RAM has found more success in writing discs for storage than in distribution because of tremendous limitations on read-compatibility of DVD-RAM media. Robotic storage libraries offering terabyte-level capacity from Asaca, Plasmon, and PowerFile have all been well-served by DVD-RAM. But more distribution-oriented purposes have not. One of the early ironies of DVD-RAM was that even its prime movers—Panasonic, Toshiba, and Hitachi—couldn't afford to market DVD-RAM-compatible DVD-ROM drives or DVD players because of the complex optics required and manufacturing costs that would price their players out of the market.

Just because DVD-R and DVD+R have a higher reflectivity that makes them more compatible doesn't mean that they are universally compatible. To date, no comprehensive list of what reads what has been compiled. The DVD+RW Alliance claims that their format is compatible with most DVD players and drives, but hedges by stating on their Web site, "there are some DVD-Players and DVD-ROM drives in the market today, especially older units, that are not capable of reading DVD+RW discs." In an attempt to resolve some of these issues, the DVD Forum released a set of hardware specifications entitled DVD Multi. This standard is intended to solve many of the compatibility questions between DVD-R, DVD-RW, and DVD-RAM by making read drives visually identifiable by their adherence to a multiformat readability standard as MultiRead (denoting CD-R and CD-RW compatibility) did for CD formats. John Spofford, chairman of the DVD+RW Alliance and an HP vice president, points out that while the standard may resolve issues for newly purchased drives, "it doesn't preserve the investment that consumers have made in DVD drives that they bought before the spec came out."

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Sorry! Notice the link is broken.
try this:http://www.emedialive.com/r18/2002/daily7_02.html
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another update 02/01/03


For those with a slow modem. I have seen an update on "Jim Taylor's Offical DVD site so here you go as well !!!

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4.3.1] Is it true there are compatibility problems with recordable DVD formats?
Yes. A big problem is that none of the writable formats are fully compatible with each other or even with existing drives and players. As time goes by they will become more compatible and more intermixed. A player with the DVD Forum's DVD Multi is guaranteed to read DVD-R, DVD-RW, and DVD-RAM discs, and a DVD Multi recorder can record using all three formats. Some new drives can write to DVD-R, DVD-RW, DVD+R, and DVD+RW, but not DVD-RAM.

In addition, not all players and drives can read recorded discs. There are lists at CustomFlix, DVDMadeEasy, VCDHelp, YesVideo.com, HomeMovie.com, and Apple that indicate player compatibility with DVD-R and DVD-RW discs. DVDplusRW.org maintains a list of DVD+RW compatible players and drives. (Note: test results vary depending on media quality, handling, writing conditions, player tolerances, and so on. The indications of compatibility in these lists are often anecdotal in nature and are only general guidelines.) Very roughly, DVD-R and DVD+R discs works in about 85% of existing drives and players, while DVD-RW and DVD+RW discs work in around 65%. The situation is steadily improving. In another few years compatibility problems will mostly be behind us, just as with CD-R (did you even know that early CD-Rs had all kinds of compatibility problems?).

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[4.3.2] DVD-R
DVD-R uses organic dye technology, like CD-R, and is compatible with most DVD drives and players. First-generation capacity was 3.95 billion bytes, later extended to 4.7 billion bytes. Matching the 4.7G capacity of DVD-ROM was crucial for desktop DVD production. In early 2000 the format was split into an "authoring" version and a "general" version. The general version, intended for home use, writes with a cheaper 650-nm laser, the same as DVD-RAM. DVD-R(A) is intended for professional development and uses a 635-nm laser. DVD-R(A) discs are not writable in DVD-R(G) recorders, and vice-versa, but both kinds of discs are readable in most DVD players and drives. The main differences, in addition to recording wavelength, are that DVD-R(G) uses decrementing pre-pit addresses, a pre-stamped (version 1.0) or pre-recorded (version 1.1) control area, CPRM (see 1.11), and allows double-sided discs. A third version for "special authoring," allowing protected movie content to be recorded on DVD-R media, was considered but will probably not happen.

Pioneer released 3.95G DVD-R(A) 1.0 drives in October 1997 (about 6 months late) for $17,000. New 4.7G DVD-R(A) 1.9 drives appeared in limited quantities in May 1999 (about 6 months late) for $5,400. Version 2.0 drives became available in fall 2000. Version 1.9 drives can be upgraded to 2.0 via downloaded software. (This removes the 2,500 hour recording limit.) New 2.0 [4.7G] media (with newer copy protection features), can only be written in 2.0 drives. 1.9 media (and old 1.0 [3.95G] media) can still be written in 2.0 drives. Version 1.0 (3.95G) discs are still available, and can be recorded in Pioneer DVD-R(A) drives. Although 3.95G discs hold less data, they are more compatible with existing players and drives.

Pioneer's DVR-A03 DVD-R(G) drive was released in May 2001 for under $1000. By August it was available for under $700, and by February 2002 it was under $400. The same drive (model DVR-103) was built into certain Apple Macs and Compaq PCs. Many companies now produce DVD-RW drives, all of which write CD-R/RW. As of fall 2002 DVD-RW drives are selling for under $200. Most DVD-RAM drives also write DVD-R discs, some also write DVD-RW discs. A few new drives write both DVD-R/RW and DVD+R/RW.

Pioneer released a professional DVD video recorder in 2002. It sells for about $3000 and provides component video (YPbPr) and 1394 (DV) inputs (along with s-video and composite). It has 1-hour (10 Mbps) and 2-hour (5 Mbps) recording modes, and includes a 2-channel Dolby Digital audio encoder.

Price for blank DVD-R(A) discs is $10 to $25 (down from the original $50), although cheaper discs seem to have more compatibility problems. Price for blank DVD-R(G) discs is $5 to $15. Blank media is made by CMC Magnetics, Fuji, Hitachi Maxell, Mitsubishi, Mitsui, Pioneer, Ricoh, Ritek, Taiyo Yuden, Sony, TDK, Verbatim, Victor, and others.

The DVD-R 1.0 format is standardized in ECMA-279. Andy Parsons at Pioneer has written a white paper that explains the differences between DVD-R(G) and DVD-R(A).

It's possible to submit DVD-R(A) and DVD-R(G) discs for replication, with limitations. First, not all replicators will accept submissions on DVD-R. Second, there can be problems with compatibility and data loss when using DVD-R, so it's best to generate a checksum that the replicator can verify. Third, DVD-R does not directly support CSS, regions, and Macrovision. Support for this is being added to DVD-R(A) with the cutting master format (CMF), which stores DDP information in the control area, but it will take a while before most authoring software and replicators support CMF.

[4.3.3] DVD-RW
DVD-RW (formerly DVD-R/W and also briefly known as DVD-ER) is a phase-change erasable format. Developed by Pioneer based on DVD-R, using similar track pitch, mark length, and rotation control, DVD-RW is playable in many DVD drives and players. (Some drives and players are confused by DVD-RW media's lower reflectivity into thinking it's a dual-layer disc. In other cases the drive or player doesn't recognize the disc format code and doesn't even try to read the disc. Simple firmware upgrades can solve both problems.) DVD-RW uses groove recording with address info on land areas for synchronization at write time (land data is ignored during reading). Capacity is 4.7 billion bytes. DVD-RW discs can be rewritten about 1,000 times.

In December 1999, Pioneer released DVD-RW home video recorders in Japan. The units cost 250,000 yen (about $2,500) and blank discs cost 3,000 yen (about $30). Since the recorder used the new DVD-VR (video recording) format, the discs wouldn't play in existing players (the discs were physically compatible, but not logically compatible). Recording time varies from 1 hour to 6 hours, depending on quality. A new version of the recorder was later released that also records on DVD-R(G) discs and can use DVD-Video format for better compatibility with existing players. Pioneer released a third generation of its DVD-RW recorder in Japan in June 2001 for about 198,000 yen (about $1,500). The new model may be released in the U.S. and elsewhere around the end of 2001 or sometime in 2002. Sharp announced a $2,200 DVD-RW recorder, and Zenith (LG) announced a $2,000 DVD-RW recorder, but neither appeared at the end of 2000 as expected. Sharp expects to have a DVD-RW video recorder that costs less than $1,000 by March 2002. TV One announced a DVD-RW video recorder for July 2001 at $3,500 that can also create Video CD discs. Sony will ship a DVD-RW video recorder in Japan in September 2001 for 220,000 yen (about $2,000).

DVD-R(G) drives released in early 2001 by Pioneer (DVR-103 and DVR-A03, priced below $1000) are combination DVD-R/RW drives. The drives also write CD-R and CD-RW discs. DVD-RW disc prices are around $15-$20 (down from the original $30). Blank media is being made by CMC Magnetics, Hitachi Maxell, Mitsubishi, Mitsui, Pioneer, Ricoh, Ritek, Sony, Taiyo Yuden, TDK, Verbatim, Victor, and others.

There are three kinds of DVD-RW discs. All are 4.7G capacity. Version 1.0 discs, rarely found outside of Japan, have an embossed lead-in (to prevent copying of CSS information), which causes compatibility problems. Version 1.1 discs have a pre-recorded lead-in that improves compatibility. Version 1.1 discs also come in a "B" version that carries a unique ID in the BCA for use with CPRM. B-type discs are required when copying certain kinds of protected video. (See 1.11 for more on CPRM; 3.11 for more on BCA.)

Note: The Apple SuperDrive (even with older 1.22 firmware) can write to DVD-RW discs, but not from the iDVD application. You must use a different software utility, such as Toast, to write to DVD-RW discs.

[4.3.4] DVD-RAM
DVD-RAM, with an initial storage capacity of 2.58 billion bytes, later increased to 4.7, uses phase-change dual (PD) technology with some magneto-optic (MO) features mixed in. DVD-RAM is the best suited of the writable DVD formats for use in computers, because of its defect management and zoned CLV format for rapid access. However, it's not compatible with most drives and players (because of defect management, reflectivity differences, and minor format differences). A wobbled groove is used to provide clocking data, with marks written in both the groove and the land between grooves. The grooves and pre-embossed sector headers are molded into the disc during manufacturing. Single-sided DVD-RAM discs come with or without cartridges. There are two types of cartridges: type 1 is sealed, type 2 allows the disc to be removed. Discs can only be written while in the cartridge. Double-sided DVD-RAM discs were initially available in sealed cartridges only, but now come in removable versions as well. Cartridge dimensions are 124.6 mm x 135.5 mm x 8.0 mm. DVD-RAM can be rewritten more than 100,000 times, and the discs are expected to last at least 30 years.

DVD-RAM 1.0 drives appeared in June 1998 (about 6 months late) for $500 to $800, with blank discs at about $30 for single-sided and $45 for double-sided. Disc prices were under $20 by August 1998, and retail drive prices were under $250 by November 1999. The first DVD-ROM drive to read DVD-RAM discs was released by Panasonic in 1999 (SR-8583, 5x DVD-ROM, 32x CD). Hitachi's GD-5000 drive, released in late 1999, also reads DVD-RAM discs. Blank DVD-RAM media is manufactured by CMC Magnetics, Hitachi Maxell, Eastman Kodak, Mitsubishi, Mitsui, Ritek, TDK, and others.

The spec for DVD-RAM version 2.0, with a capacity of 4.7 billion bytes per side, was published in October 1999. The first drives appeared in June 2000 at about the same price as DVD-RAM 1.0 drives. Single-sided discs were priced around $25, and double-sided discs were around $30. DVD-RAM 2.0 also specifies 8-cm discs and cartridges for portable uses such as digital camcorders. Future DVD-RAM discs may use a contrast enhancement layer and a thermal buffer layer to achieve higher density.

Samsung and C-Cube made a technology demonstration (not a product announcement) in October 1999 of a DVD-RAM video recorder using the new DVD-VR format (see DVD-RW section above for more about DVD-VR). Panasonic demonstrated a $3,000 DVD-RAM video recorder at CES in January 2000. It appeared in the U.S. in September for $4,000 (model DMR-E10). At the beginning of 2001, Hitachi and Panasonic released DVD camcorders that use small DVD-RAM discs. The instant access and on-the-fly editing and deleting capabilities of the DVD camcorders are impressive. Panasonic's 2nd-generation DVD-RAM video recorder appearing in October 2001 for $1,500 also writes to DVD-R discs.

The DVD-RAM 1.0 format is standardized in ECMA-272 and ECMA-273.

[4.3.4.1] How do I remove a DVD-RAM type 2 disc from the cartridge?
Type 2 DVD-RAM cartridges allow the disc to be removed so that it can be played in standard players or drives. (However, most players and drives still won't be able to read the disc -- see 4.3.1.)

First break (yes, break) the locking pin by pushing on it with a pointed object such as a ballpoint pen. Remove the locking pin. Unlatch the cover by using a pointed object to press the indentation on the back left corner of the cartridge. Data is recorded on the unprinted side of the disc -- do not touch it. When you put the bare disc back the cartridge, make sure the printed side of the shutter and the printed side of the disc face the same direction.

Most DVD-RAM drives will not allow you to write to a bare disc. Some will not allow you to write to a cartridge if the disc has been removed.

[4.3.5] DVD+RW and DVD+R
DVD+RW is an erasable format based on CD-RW technology. It became available in late 2001. DVD+RW is supported by Philips, Sony, Hewlett-Packard, Dell, Ricoh, Yamaha, and others. It is not supported by the DVD Forum (even though most of the DVD+RW companies are members), but the Forum has no power to set standards. DVD+RW drives read DVD-ROMs and CDs, and usually read DVD-Rs and DVD-RWs, but do not read or write DVD-RAM discs. DVD+RW drives also write CD-Rs and CD-RWs. DVD+RW discs, which hold 4.7 billion bytes per side, are readable in many existing DVD-Video players and DVD-ROM drives. (They run into the same reflectivity and disc format recognition problems as DVD-RW.)

DVD+RW backers claimed in 1997 that the format would be used only for computer data, not home video, but this was apparently a smokescreen intended to placate the DVD Forum and competitors. The original 1.0 format, which held 3 billion bytes (2.8 gigabytes) per side and was not compatible with any existing players and drives, was abandoned in late 1999.

The DVD+RW format uses phase-change media with a high-frequency wobbled groove that allows it to eliminate linking sectors. This, plus the option of no defect management, allows DVD+RW discs to be written in a way that is compatible with many existing DVD readers. The DVD+RW specification allows for either CLV format for sequential video access (read at CAV speeds by the drive) or CAV format for random access, but CAV mode is not supported by any current hardware. DVD+R discs can only be recorded in CLV mode. Only CLV-formatted discs can be read in standard DVD drives and players. DVD+RW media can be rewritten about 1,000 times (down from 100,000 times in the original 1.0 version).

DVD+R is a write-once variation of DVD+RW, which appeared in mid 2002. It's a dye-based medium, like DVD-R, so it has similar compatibility as DVD-R. Original DVD+RW drives did not fulfill the promise of a simple upgrade to add DVD+R writing support, so they have to be replaced with newer models. The original Philips DVD+RW players, on the other hand, can be customer-upgraded to write +R discs.

Philips announced a DVD+RW home video recorder for late 2001. The Philips recorder uses the DVD-Video format, so discs will play in many existing players. HP announced a $600 DVD+RW drive and $16 DVD+RW discs to be available in September 2001. HP's drive reads DVDs at 8x and CDs at 32x, and writes to DVD+RW at 2.4x, CD-R at 12x, and CD-RW at 10x. Sony announced a $600 DVD+RW/CD-RW drive in October 2001.

DVD+RW media is being produced by CMC Magnetics, Hewlett-Packard, MCC/Verbatim, Memorex, Mitsubishi, Optodisc, Philips, Ricoh, Ritek, and Sony.

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