MCCB with ELCB & RCCB are perform equal operation

ELCB (earth leakage circuit breaker) and RCCB (residual current circuit breaker) are two names for devices that do the same sort of thing: in the event of an imbalance between the supply and the return conductor, assume a fault to earth and disconnect the supply for safety. The imbalance rating is typically 30mA, though not always.

MCCB stands for moulded case circuit breaker, which does not necessarily have an earth current facility, and is used for overcurrent protection. They are typically found in the supply conductor only.