* Crankshaft pulley: The largest pulley, directly connected to the crankshaft.
* Power steering pump pulley: Drives the power steering pump.
* Alternator pulley: Drives the alternator.
* Air conditioning compressor pulley (if equipped): Drives the A/C compressor.
* Water pump pulley: Drives the water pump.
To know which pulley you're asking about, you need to specify which component it's attached to (e.g., "the alternator pulley," "the crankshaft pulley").