Not a lot but there is enough to make a good bit of difference in handling. The 8.5 is a longer chassis 2mm front and 2mm rear. It all so comes with some hop ups that needed to be added on the 8 like center diff brace and longer engine mounts to cut down on chassis flex. There are some other things as well but those are the main things If all you do is bash no big deal but if you race the 8.5 pro is MUCH better. I have both the 8 pro and 8.5 pro. Have not run them in about 10 months as I have been racing large scale.