From what I remember, DVD-R is the slightly more compatible format. It's best to get one of each and just try it out on whatever hardware you've got. They're both not guaranteed to work in all DVD-ROM drives or DVD players.

You just put whatever media you want into the drive. The actual data on the disc is identical.

So now there is DVD-R, DVD-RW, DVD+R, DVD+RW, DVD-RAM... any others I've missed?

- Trevor