If you're comparing to the first Adam Drake edition, the major differences are that all the plastic parts are instead graphite. Most of the aluminum parts, including chassis and pipe are hard anodized. The geometry of both trucks is the same.
If you're comparing to the new AD2, then there are really too many differences to list. You wouldn't want to try to upgrade to this. It would cost far more than buying the kit itself. The AD2 is beefed up in quite a few places, for durability.