The SPS has a much coarser finish on it, while the XCR is polished w/a corrosion inhibiting coating on it.
Instead of polishing, it appears that Rem simply bead blasts the SPS action...knocking off the burrs and bumps in one simple process.
Still equally as functional, just arguably not as pretty.
As for the stock... as far as I can tell the SPS is the same as the XCR with the exception of a rubber overmoulding in the areas one would normally find checkering in the grip/forend.
Accuaracy/function wise... same rifles though.
The SPS is a hell of a value!
280_ACKLEY