To make it really short, the differences are:
1. One part on the sheet of photo-etch
2. Decal sheets. The one from Academy is smaller with fewer individual vehicles (2 options vs 6 one the AFV Club sheet)
3. The instruction sheet. The Academy version is a folded sheet and the AFV Club one is a booklet. The sequence of assembly is and the diagrams are the same but divided up into different steps (example: step 6 by Academy mounts the wheels and AFV Club has this as step 8 ).

The only real difference is the box over the exhaust (the grille on the forward right hand side top hull).
AFV-Club provides PE-part M1 which is a "flat" mesh with 9 corners. Academy has removed this part and provides a complicated part with integrated mesh that needs to be folded along several lines to create the "box" that goes
over the exhaust.

The M1126 by Academy is not directly interchangeable with the kit by AFV-Club due to the absence of part M1 (the mesh).

/ Robin

Id stick with the Academy , rather then the AFV. I'm not a fan of AFV . lots of unnecessary complicated parts !

How expensive is it?

Here is the thing. No difference between thise two brands stryker because academy use AFV club molds.

Louis, good luck with that as the Academy kit IS the AFV Club kit but with the differences as outlined by Robin.

The exhaust cover Academy provides is just the armored exhaust cover. I did like Academys decal selection- more variety