Both single-phase permanent capacitor (PSC) motors and capacitor start capacitor run (CSCR) motors are types of AC induction motors that are commonly used in various applications. However, the key difference between them is in the way they are started and the role of the capacitor in their operation.

Single-phase permanent capacitor (PSC) motors are designed to operate with a single capacitor that is permanently connected in the starting winding. The capacitor is used to create a phase shift between the starting and running windings of the motor. The motor is started by applying a voltage to the starting winding, and as the motor speed increases, the capacitor provides the necessary additional phase shift to allow the motor to continue running. PSC motors are simple and reliable, but they are less efficient than other types of AC induction motors. PSC motors commonly used in applications where low starting torque is required, such as fans and blowers.

Capacitor start capacitor run (CSCR) motors, on the other hand, are designed with two capacitors - a start capacitor and a run capacitor. The start capacitor is used along side the run capacitor to create a high starting torque, and once the motor reaches a certain speed, a switch disconnects the start capacitor. CSCR motors commonly used in applications where high starting torque is required, such as air conditioning units, compressors, and pumps.