Pump is having inpellors but the ship and helicoptor having propellors

Hi, kgpreman!

A propeller is on the outside, i.e. external like on the outboard motor of a boat, hellicopter or airplane.

An impeller is on the inside, i.e. internal like inside the water pump.

Thanks!

Impeller- the machine move the fluid.
Propeller- the machine use the fluid to move itself
Ussually propeller having less blade than impeller

An impeller is a rotor inside a tube or conduit used to increase the pressure and flow of a fluid.

A propeller is a type of fan which transmits power by converting rotational motion into thrust.

Both impeller and propeller are used in the pumps for various applications. Generally impllers are being used for generating more pressure with lower flows while propeller for low pressure with high flows.