Read-Only DVD drives (DVD-ROM)
A DVD-ROM only reads information from DVDs, but cannot record on them. It allows users to watch movies, play music, or transfer files from DVDs to a computer. It can read all DVD formats including DVD-video, DVD-R, DVD+R, DVD-RW, and DVD+RW, except DVD-RAM. Most models require special software to play DVD-video files since these files use MPEG-2 compression.
Random Access DVD drives (DVD-RAM)
A random access DVD drive can read all DVD formats and write on DVD-RAM media. It provides an additional storage unit for data. It cannot burn DVD-audio and DVD-video formats.
Recordable DVD drives (DVD-R)
A recordable DVD drive can read, play, and write data on DVD-R discs. It can only be written on once; the recorded data cannot be erased or overwritten. It can read CD-ROM, CD-R/RW, DVD-ROM, and DVD-R/RW media.
Rewritable DVD drives (DVD-RW)
A rewritable DVD drive can write and rewrite data on DVDs. It can erase the data currently stored in a DVD disc and rewrite new data several times. It can read CD and DVD media in all formats, except DVD-RAM. It writes data in continuous streams, making it ideal for recording content from televisions and other video devices just like a VCR.