Chain drives and belt drives are both power transmission mechanisms, but they differ in their design and efficiency. Chain drives use a series of metal links connected by pins to transmit power from one sprocket to another, while belt drives use a continuous loop of material (such as rubber or leather) that runs over pulleys.
The efficiency of a power transmission system is a measure of how much of the input power is actually transmitted to the output. Chain drives are generally more efficient than belt drives, with efficiencies of up to 98%. This is because chain drives have less slippage than belt drives. Belt drives can slip if the belt is not tensioned properly, which can lead to a loss of power.