This article is from the CD-Recordable FAQ, by Andy McFadden (firstname.lastname@example.org) with numerous contributions by others.
CD-ROMs and music CDs you commonly find in stores are pressed from a
glass mold. CD-Rs are burned with a laser. They may look different (often
green, gold, or blue instead of silver), they're less tolerant of extreme
temperatures and sunlight, and they're more susceptible to physical damage.
Whether CD-Rs or pressed CDs last longer is difficult to answer.
While they're not physically identical, they work just the same. Some CD
players and CD-ROM drives aren't as good at reading CD-R and CD-RW discs as
they are at reading pressed CDs, but by and large they work just fine.
By the way, you can't record on pressed discs, so you might as well throw
out all those AOL CD-ROMs you've been accumulating (or try one of the
suggestions in section (7-9)). Buying a bunch of old CDs in the hopes of
writing new stuff onto them is a bad idea. For similar reasons you can't
record on DVD media, not even DVD-R and DVD+RW, unless your drive explicitly
supports the DVD formats. You have to buy blank CD-R or CD-RW media.