Not a lot. They are basically the same with the same functions (ALS, launch control, closed loop boost and fueling, cooling fan control, EGR, air con, single cylinger fuel and ignition trim, datalogging etc etc) but the processor in the T6 became obsolete so they started using another. They can still upgrade T6 to 2000. There are some minor little differences in that the 2000 has the abillity to do some wierd functions that most people will never ever use (can't remember what they are now, just remember them being a bit obscure).