The ECU on both is a ME 2.0 / ME 2.1 but of a different calibration.

The C36 trans has a different gear ratio set than the C280 sport / non sport. Given the C36 has more power, it does not need such deep gear ratios and uses ratio from the V8 cars. This means that the trans controller has a different calibration as well.

I'm not sure if the rear ratio is different between the C280 and C36.