BOILERMAKER 0 Newbie Poster

I have been reading some archived posts and just want to make sure I understand this correctly. These are the two drives I currently have:
JLMS DVD-ROM XJ-HD166 and Phillips DVD+RW DVD8601 I have been having great difficulty writing back up DVDS and movie DVDS. Now that I have read some posts I think the problem may be that I have been using DVD+R discs. So is it accurate to say that I can only save data on DVD+RW discs with my current drives? I have been able to save data to CD-R discs though, why do they work?