The differences between BT1 and BT7 are that both are from different years of the Rally Championship. BT7 has different wheels and an airdam above the front windscreen, different sponsor markings and the extra missle launcher. The bodywork is also different with the front bumper remolded with a different front intercooler and side airvents. Personally I prefer the look of BT1 but I got BT7 as well because of the completist in me.