A contactor is an electrically-controlled switch used for switching an electrical power circuit. It is typically used for controlling electric motors, lighting, heating, and other electrical loads. Contactors are designed to handle high current loads and are durable enough for industrial use.

A relay is an electromagnetic switch that opens and closes circuits electromechanically or electronically. It allows a low power signal to control a high power circuit. Relays are used in automation, electronics, and power systems for switching, protection, and logic operations.