If it is toward the front of the engine (water pump as an example), chances are it is belt driven. If it is toward the rear of the engine (air compressor), chances are it is gear driven.

Is the water pump belt or gear driven?

Water Pump: belt driven, securely mounted, not leaking.

Is the power steering pump gear driven?

First, heavy duty power steering components are much larger in size than light duty parts. This should be the most easily identifiable difference between pumps and gears for light and heavy classes. Heavy duty pumps are gear driven, as opposed to light duty parts, which are belt driven.