There are different types of circuit breakers and they are different in their construction. However, the overall and the common matter of a circuit breaker is that it consists of multiple movable and fixed contacts similar to an electrical contactor, but they usually contact physically through pneumatic and mechanical pressure or electromagnetic attachment. The circuit breaker has voltage and current sensing circuits which is missing in a contactor. This is because a circuit breaker is operated automatically, and it works all by itself when a fault appears.