Forza is for more for ricers, putting on body kits and pointless wings. GT is for car fans to screw around with stuff they cant see.
GTs cars react and handle more realistic, ex body roll while under heavy breaking. Also more realistic sounds.
GTs is made by car lovers, Yamauchi loves cars owns a few top end makes. Forza not so much.
GT has the backing and blessing of major manufacturers, works with them gets special treatment and access to cars. Forza does not. Thats why GT features concept cars that are not just for show but drive like the actual concept. GT is allowed access to sensitive info about cars from many of these manufacturers.
Forza caters to a more arcade type crowd that wants to drive fancy super cars, GT is more focused on the import crowd the lover of Skylines Supras Evos what not. These people want to drive the car in the game they own in real life.







