What is the difference between pulleys and gears?

Answer 1

Pulleys (and their cousins, sheaves) transmit power through their connection to one another by way of belts or ropes. Pulleys are often used as a lever system to gain mechanical advantage, and often one or more of them will move in a linear fashion when doing so. Gears are like pulleys or sheaves in that they also transmit power, but do so by way of being in direct contact (meshed) with each other. In either case, rotating shaft speeds can be sped up or slowed down relative to other parts of the system by varying the size of the pulley or gear. Smaller driven units will rotate faster than larger ones for a given size of driving unit.

Answer 2

Both pulleys and gears are used to transfer motion from one shaft to another, but they operate in different ways. Pulleys use a belt or rope to transmit motion, while gears use interlocking teeth. Pulleys are better for applications where smooth movement is required, while gears are better for high torque or precision.