I mean the ones in the dealershipYou mean the 15th AE cars or the actual race cars in the dealership? The 15 AE cars have a lighter weight and a little more hp so handling adjustments have to be made, but nothing too bad with the exception of the Huayra, takes some time getting used to.
The ones in the dealership (McLaren F1 Base, McLaren F1 Japanese Text Racing Team) are absolutely the same. Same weight and hp, both have extreme amounts of grip, only difference is you can paint the McLaren F1 Base in neon green.