I have only basic knoweledge but for those who may have less knowledge than me this is what i know.
dvd's and cd's come in the same formats
For example DVDR and CDR = the R means you save data to them but it is then stuck on there, you cannot remove it so if you save the wrong stuff on your disk your 'stuffed' you have to leave it and use another disk.
DVDRW and CDRW = the RW means you can rewrite the data so it is like a recharable battery you can keep re-using it for differient things time after time. These are twice the price of R disks.
You have to also know whether you recorder uses (-)negative or (+)possitive disks it will tell you in your manual or basically it told me on the side of the box of discs, it showed which makes use (-) and which ones (+) format, but I do not know how reliable this is.