The different variations on the term DVD +R, -R etc describe the way data is stored on or written to the disc itself. These are called physical formats.
DVD+R and DVD+RW
DVD+R and DVD+RW formats are mainly supported by Philips, Sony, Hewlett-Packard, Dell, Ricoh and Yamaha.
DVD+R often called "plus R" can record data only once as the data becomes permanent on the disc.
The single sided discs can hold 4.38 GB with double sided discs holding twice as much.
There are also dual layer single sided recordable discs.
This format competes with the DVD Forum DVD-R specification.
DVD+RW is a ReWriteable media format of the DVD+R standard.
DVD-R, DVD-RW and DVD-RAM
These formats are supported by Panasonic, Toshiba, Apple Computer, Hitachi, NEC, Pioneer, Samsung and Sharp. They are also supported by the DVD Forum.
DVD-R
is a recordable DVD format similar to CD-R and DVD+R.
A DVD-R can record data only once as the data becomes permanent on the disc.
Is compatible with most DVD drives and players.
There are also dual layer single sided recordable discs.
Capacity is 4.7GB.
This format competes with the DVD+R format.
There are also two additional standards for DVD-R discs: DVD-RG for general use, and DVD-RA for authoring, which is used for mastering DVD video or data and is not typically available to the general public.
DVD-RW
is a phase-change erasable format.
Developed by Pioneer based on DVD-R, using similar data arrangements, DVD-RW is playable in many DVD drives and players.
Capacity is 4.7 GB.
DVD-RW discs can be rewritten about 1,000 times.
DVD-RAM
discs can be recorded and erased repeatedly but are only compatible with devices manufactured by the companies that support the DVD-RAM format.
DVD-RAM discs are typically housed in cartridges.
Supports 100,000 re-writes.
DVD+R DL and DVD-R DL
Dual layer technology is supported by a range of manufacturers including Dell, HP, Verbatim, Philips, Sony and Yamaha.
As the name suggests, dual layer technology provides two individual recordable layers on a single-sided DVD disc.
DVD+R DL (also called DVD+R9) is a Dual Layer writeable DVD+R.
DVD-R DL (also called DVD-R9) is a Dual Layer writeable DVD-R.
The dual layered discs (DVD+R9 and DVD-R9) can hold 7.95GB and double sided dual layer discs (called dvd-18) can hold 15.9GB.
DVD-ROM
DVD-ROM was the first DVD standard to hit the market and is a read-only format.
The video or game content is burned onto the DVD once and the DVD will run on any DVD-ROM-equipped device. DVD-ROMs are similar to CDs.
Blu-ray Disc (BD)
High definition
uses a 405nm-wavelength blue-violet laser technology, in contrast to the 650nm-wavelength red laser technology used in traditional DVD formats. The rewritable Blu-ray disc, has a data transfer rate of 36Mbps (1x speed).
A 50GB disc translates into 9 hours of high-definition (HD) video or approximately 23 hours of standard-definition (SD) video.
BD-R Single layer 25GB or 7.8GB
BD-R Dual layer 50 GB or 15.6GB
BD-RE Single layer Rewriteable 25 GB or 7.8 GB
BD-RE Dual layer Rewriteable 50 GB or 15.GB
The Blu-ray format was developed jointly by Sony, Samsung, Sharp, Thomson, Hitachi, Matsushita, Pioneer and Philips, Mistubishi and LG Electronics.
Advanced Optical Disc
High definition disc competing with Blu-ray
AOD and Blu-ray are similar in that they both use 405nm-wavelength blue-violet laser technology. Whilst Blu-ray has a storage capacity of 25GB on a single-layer disc, AOD has a storage capacity of 20GB on a single layer disc and the capacity to hold 30GB on a dual-layer disc.
AOD was developed jointly by Toshiba and NEC.