What is the difference between an AC motor and a DC motor?

Power = voltage x current for direct current (DC motor) systems. For alternating current (AC motors) systems the instantaneous voltage and current are constantly changing (alternating in the form of a sine wave).

Power = voltage x current for direct current (DC motor) systems. For alternating current (AC motors) systems the instantaneous voltage and current are constantly changing (alternating in the form of a sine wave). The power associated with an AC system will be less than that of a DC system with the same current and voltage because these values are constantly changing and without correction, they are out of phase. There is a power factor that is based on the phase angle between the current and voltage that must be included in the power equation for an AC system. This power factor is always less than 1.0 in an AC motor and can be as low as 0.5 or even lower. Unless very expensive power factor correcting equipment is used, the power for an AC system will be significantly different from the power for an equivalent DC system.