An exclusive distributor is appointed to be the only distributor within a specified territory. Even the supplier cannot make sales in that territory.
A sole distributor is the only distributor in a specified territory besides the supplier. Only this distributor and the supplier can make sales in that territory.
A non-exclusive distributor is not an exclusive or sole distributor within a territory. This means that the supplier can make sales in the specified territory and may also appoint other distributors to do so (or other distributors may already be active in the territory).