for the basics the srx is a low slung lake racer with about 7" travel front and rear. the sxr is more cloned from the snowcross style sleds with around 9" travel up front and over 11" in the rear.
in the skid they use different shocks, different transfer rods, different front pivot arms, different length limiter straps, just to name a few key components.
up front the rad rods are different lengths and have different angles on them. tie rods are longer for the sxr, trailing arms are different to a degree, and obviously the shocks are different.
sxr is much more capable as a rough trail or ditchbanger as the srx fall short in the rough stuff do to lacking in suspension travel. two differently designed machines for 2 different disciplines of riding.
just a light touching on the main suspension differences, what else you need to know?