In low-voltage power distribution systems, circuit breakers are indispensable protective devices. However, many people's understanding of circuit breakers stops at the basic concept of "tripping protection," without realizing that different types of circuit breakers vary enormously in performance and application. The MCCB (Moulded Case Circuit Breaker) and the MCB (Miniature Circuit Breaker) both belong to the circuit breaker family, yet their roles are fundamentally distinct—one is a "heavy-duty solution" designed for industrial high-current scenarios, while the other is a "compact guardian" serving residential and lighting circuits.