Learn the difference between agitator and impeller washers to determine which is right for you. Both agitator and impeller washers have great cleaning performance, energy efficiency, and capacity, but they clean clothes in very different ways. Agitators use a finned central post that twists back and forth and rubs against clothes to loosen soils. Impellers use a low-profile disc that spins, causing clothes to rub against each other to clean them.