Gravity advantage or gravity advantage max.

[Almond]

I went over to elasticsteel site to see the gravity advantage book. There are two of them there. From what I read on the gravity advantage is just upper body conditioning. That book teaches how train all upper body muscles with just bodyweight and no equipment.
I am not sure what gravity advantage max does. Some people on elasticsteel forum said that gravity advantage should be before gravity advantage max. I am guessing that gravity advantage max is harder.
I read that some people on here have both books. Thanks for replies.

[Appleman]

You don't have do GA exercises at a pre-requisites to GAM.