Couldn't find that thread, so I just searched a little.
DVD-R is not the same as
DVD+R. Another good source is
http://www.cdfreaks.com/article/113.
From what little I read, DVD+R has a better sound quality due to the way it's recorded (the tracking, addresses, and speeds), and DVD+R was also used to make the dual layer (8.5gb) DVD's.
Feel free to correct and/or to add to this, I'm sure it'd be appreciated.