What's the difference ? Is one better than the other?

Go here and it will tell you all you want to know about DVD formats --
http://www.videohelp.com/dvd

more links:
Link #1
Link #2

and personally, i've always choose the "+" as my most preferable format.

All new drives will take both....buy the one your dealer has on sale.
If you have an OLD drive, get the one your drive calls for.

Don't get all excited about a difference that no longer makes any difference.

I use both on my new DVD DL drive. They both just work. The drive seems to not give a darn.

Merry Christmas,
Andromeda43

yes, you're right back there Andromeda43.
but in term of technology, the "+" camps always ahead.
wobbling, addressing information, design revisions etc etc etc

and yes, i used both format with my (dl +- dvd burner)