DVD-RAM is a rewritable and recordable DVD type designed by Toshiba, Panasonic, and a few other companies. It comes in non-cartridge and cartridge forms, double- or single-sided with 4.7GB of memory storage per side. DVD-RAM discs are very helpful for backups similar to a hard drive as they can be rewritten for almost 100,000 times, 100 times more as compared to either DVD+RW or DVD-RW. On the other hand, DVD-RAM is not as widely used as DVD R/RW discs and can be played only on some camcorders, DVD-RAM drives, and video recorders. It is not supported by most DVD-Video players and DVD-ROM drives.
DVD-ROM is a read-only DVD video format and holds almost 4.38 GB of data that is pre-recorded by the companies and cannot be rewritten, changed, or erased. This type of DVD is widely used for software applications and movie rentals. DVD-ROM discs can be read with a DVD-ROM/DVD-RAM drive by a computer, but not on a DVD drive linked to a TV or home theater system.