The command Slew orders the telescope to move to a particular target, and once the telescope reaches its target, the telescope keeps tracking that target at a sidereal rate (i.e. the rate at which stars move across the sky). This works well for stars, Messier objects, and about everything outside our solar system. But solar system objects travel differently across the sky and so the telescope must Track the objects as they move. Therefore, you need to issue a track command if you want to track an object with non-sidereal motion. On the other hand, Sync is used to synchronize the telescope’s internal coordinates with that of an object you select.