Academy's and Tamiya's both build into M2A2 ODS vehicles from about '03-'04. Tamiya's represents an older, rebuilt vehicle, while Academy's is a new-build, early M2A2 ODS. The Academy one is a little more up to date and more refined than Tamiya's. However, Academy's has the wrong tracks for a modern Bradley. It still has the triangular block track from their original M2 kit. Modern Brads, since the mid-'90s, have rectangular block tracks. AFV Club has a really nice plastic track set, Fruil also does metal tracks for it.
The Big Ed set, unless it is new, is really for the original M2 kit with interior, exterior, and turret details, along with a mask set. It is still useful, but has many obsolete parts on it. The turret interior is nice though.
Check out
Pavel's Bradley Article for some updates and corrections that can be applied to either kit.