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The formats for compact disc were laid down in a number of coloured books, based on inventions and inspiration from Philips, Sony and a number of other companies and administered by Philips in Eindhoven. This table attempts to show how these books relate to each other in a (somewhat) simplified way. Other related standards are shown as well.
DVD is much simpler. A DVD disc is always a DVD-ROM disc and becomes DVD-Video or DVD-Audio if it has suitable material in specified directories (see the DVD FAQ). There are two writeable formats (DVD-R and DVD+R) and three competing (and sometimes incompatible) re-writeable formats - DVD-RAM, DVD-RW and DVD+RW. These disc types are incompatible only when it comes to writing them. Usually, machines that play back any DVD format will now play them all back (with DVD-RAM being the least compatible). There are even DVD video players which pride themselves on being able to play back 'anything that rotates'.
There are currently two competing formats proposed for higher-capacity DVDs, aimed at high definition television as well as computer storage.
Early DVD-ROM drives were unable to read many CD-R discs but the current ones can read all CD formats, usually including the rewriteable formats. The 'ultimate' are the so-called Super Drives which initially combined DVD-R, DVD-RW, DVD, CD-R and CD-RW but have now extended their range to include the DVD+R and DVD+RW formats. Dual layer writeable DVDs are the latest format to appear, offering twice as much storage again!
Writeable DVD systems have dropped in price from thousands to a hundred or so dollars in the past few years. while CD-Writers are now available as consumer items at remarkably low prices aimed at both the music and computer markets. CD-R discs themselves are now extremely cheap and DVD discs are not much more expensive. The aim is for re-recordable DVD discs to be used by home consumers as a replacement for videocassette machines for both time-shifting and watching movies either in conjunction with a hard disc recorder or stand-alone. Consumer DVD video recorders like this are available.
A final format to note is SACD. These are pre-recorded discs, like CD audio discs, with up to multitrack audio content. In many ways they are like DVD-Audio but they usually contain an SACD layer and a CD layer, so the discs are (in theory) backwards compatible to CD audio players. The recorded bit-stream is different to DVD-Audio as well. DVD audio uses a high-specification version of 'straight' PCM audio as used on CDs, while SACD uses a delta-coded format. The golden ears are undecided as to which is the better format (and I can't tell the difference).
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Book 2 Chapter 5 - Platform parameters
