This goes WAY beyond what Orbiter is capable of. They modelled pretty much EVERY button, switch, readout, etc on that shuttle flight deck. It was YEARS in the making. Also, the aerodynamic model is FAR more accurate than the one in Orbiter. Scenery is also better and looks a lot more realistic than in orbiter (but that's a minor point).
As far as a true space shuttle simulation, Space Shuttle Mission is far beyond Orbiter in modelling the shuttle. I've flown both sims (Orbiter is still responsible for my blowing hours of my time
. It's a great sim) and for the shuttle simulation, it just doesn't get more accurate than Space Shuttle Mission.
Try the demo. You won't be dissapointed (Just make sure to read the manual first.)