I'll assume you are talking about "hi" and low? the main difference is clutching, and usually pulley combinations (boost level) along with a different tune. There usually isn't much to switch them back and forth, and if you keep good notes, you can put your sled back to either configuration pretty quickly.
I don't think for most, that the boost level is much different either, but it could be a little just to compensate for thinner air at higher altitudes.