The SL and the Compact both use automap universal and both have semi-weighted keys with aftertouch.
The main difference is the number of controls, the SL has sliders and more buttons and knobs. Whereas the Compact has less button and knobs, but it has bigger drum pads and a speed dial function.
Also, the SL features a touchpad and mod/pitch joystick whereas the compact just has the traditional mod and pitch wheel. And most obviously, the SL has 2 large display and the Compact only has 1.
More information can be found here: