Well I'm actually not sure what the differences are, but what happened is the some of the manufacturers supported one standard, and other decided to support the other standard.
I know that isn't very clear, but that is the best that I can do.
Your 107D drive is capable of supporting both the + and the - standard, so you can pick and choose as you wish.
Your SuperDrive IS compatible with both types of media, but OS X is NOT. To get the best compatibility, choose DVD-R or DVD-RW. OS X can read DVD+R/W, and I believe that the Finder only can write to DVD+R/W, but I know for a fact that all iApps (iDVD, iPhoto, etc.) and the Finder can read and write DVD-R and DVD-RW.
That isn't entirely accurate, yes the natively supported standard by Apple is the - standard.
Yes the iApps don't support the + standard, but there have been some reports on Disk Utility being able burn + media. And of course toast supports both standards.