The benefit of a vortex impeller over a channel impeller is the minimised risk of clogging.
The vortex impeller creates a revolving mass of water which forms a whirlpool. A whirlpool is a funnel shaped opening is created downward from the water surface. It can be developed by water flowing out of a small opening in the bottom of a basin, a reservoir or by a pump.
Impellers creating this Vortex are called vortex impellers. The benefit of a vortex impeller over a channel impeller is the minimised risk of clogging. A Vortex impeller is also a better choice when the pumped liquid has a high content of sand.
The efficiency of a pump with a vortex impeller is typically lower than a pump with a channel impeller.