Hi. AC motors are designed and built differently than DC motors. AC motors take advantage of the 60 hertz clock of a power line (or 50Hz in other countries) - this means the power line changes phases 60 times a second - to rotate, while DC motors are designed with the voltage level applied. You can control them both, but with different means. The easiest to control is the DC motor (change the potential (the voltage) and it turns slower or faster.
DC motors usually have brushes to commutate (or rotate) the magnetic fields as the rotor turns. AC motors are brushless because commutation occurs automatically from the sinusoidal nature of the electrical fields.
