What's the actual diference between DVD-R and DVD+R disks?

[Richard_G]

I know all about the different arguments between the two types, I also know that my Pioneer A05 is a DVD-R drive. What I would like to know is what is the actual difference between unburnt blank disks? They are the same size, have the same capacity and are made of plastic with a dye coating that you burn with a laser. I assume there must be a difference between the two when they are manufactured otherwise you would just buy DVDR disks and the difference wouldn't happen until you burnt something on them.

I assume that they might be preformatted or something similar, in the same way as a floppy disk formatted for a pc won't work in a Mac (or they didn't used to, they probably do these days).

Anyone know what the difference is?

[tompika]

http://www.cdfreaks.com/article/113