There's no real answer to that one. In most European major airlines, anywhere within about 4 hours would be flown by the shorthaul fleets on shorthaul aircraft. The longhaul fleets would, generally, not fly any sector below about 5 hours (unless it is what is called a "shuttle" at a long haul destination - we used to fly, for example, Sao Paulo to Rio De Janeiro and back in a day as a shuttle in the middle of the London to Sao Paulo trip). I reckon just about anything inside Europe and to the west of the Urals as shorthaul.