An electric clock is probably one of the most reliable motors. The small motor uses very little electricity. The clock is made of a case to hold the motor, the motor, a time-set knob, alarm lever, alarm mechanism, gear assembly, dial light, face, hands, some type of covering, and the power cord. An electric clock works because the motor turns gears, which in turn, move the clock hands. Some clocks have metal gears, while others have plastic.
Plastic gears tend to be quieter, and are used by most modern manufacturers.
Digital clocks rely on electronic circuitry, instead of gears. Electricity powers an electronic control panel, which posts the time. While they work well, they are difficult to fix. If you have problems with your digital clock, you will likely have to replace it. Digital clocks also must be set, and will need to be reset with a break in power.