What’s the difference between a super charger and a turbo?

In cars and motorbikes, superchargers and turbochargers both use rapidly spinning impellors (rotors) to suck extra air into the engine, causing bigger explosions in the cylinder when the fuel is ignited. In a supercharger, the impellor is driven directly by the engine crankshaft. But in a turbocharger, the power is taken from the exhaust gasses leaving the engine.