Kbase Article of the Week: Power Macintosh: Differences Between DVD-ROM, DVD-RAM and DVD-RW →

Apple Support:

DVD-ROM, as its name implies, is a “read-only memory” format. Your computer can read a disc’s contents, but it cannot save data to one.

DVD-RAM (DVD random-access memory) and DVD-RW (DVD rewritable) are both rewritable mediums. Both DVD-RW and DVD-RAM are rewritable DVD standards that have been published by the DVD Forum, a group of more than 200 industry-leading corporations.

This article then links to a second article titled “SuperDrive: About Rewriteable DVD Discs,” which goes into a lot more detail. It ends with this note:

Important: Information about products not manufactured by Apple is provided for information purposes only, and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.