A three phase Synchronous motor is a doubly excited machine, whereas an induction motor is a single excited machine. The armature winding of the Synchronous motor is energized from an AC source and its field winding from a DC source. The stator winding of Induction Motor is energized from an AC source. Synchronous Motor always runs at synchronous speed, and the speed of the motor is independent of load, but an induction motor always runs less than the synchronous speed. If the load increased the speed of the induction motor decreases. The induction motor has self-starting torque whereas the synchronous motor is not self starting. It has to be run up to synchronous speed by any means before it can be synchronized to AC supply. A synchronous motor can be operated with lagging and leading power by changing its excitation. An induction motor operates only at a lagging power factor. At high loads, the power factor of the induction motor becomes very poor. The Synchronous Motor can be used for power factor correction in addition to the supplying torque to drive mechanical loads whereas an induction motor is used for driving mechanical loads only. The synchronous motor is more efficient than an induction motor of the same output and voltage rating. A synchronous motor is costlier than an induction motor of the same output and voltage rating.