XT cranksets were machine finished and had thicker better quality rings, considerably higher in quality over DX
XT rear mechs had aluminium parrallelagrams, DX was alu and steel
XT had cermamic bearing jockey wheels and all aluminium cages, DX were steel/ alu/ standard j/wheels.
XT cantis had better finish pad holders
The hub bodies were the same design but XT had greaseports and better finish axles.
front mechs had superficial differences from 500LX through till XT