MCB - Miniature Circuit Breaker
MCB is miniature circuit breaker which is thermal operated and use for short circuit protection in small current rating circuit.
Normally it is used where normal current is less than 100 A
MCCB - Moduled Case Circuit Breaker
MCCB moduled case circuit breaker and is thermal operated for over load current and magnetic operation for instant trip in short circuit condition.
Under voltage and under frequency may be inbuilt. Normally it is used where normal current is more than 100A