EMU or Electric Multiple Unit is a Local Train meant for Suburban Travel within a Metropolitan City/Region like Kolkata, New Delhi, Chennai or Mumbai and has no Toilet Facility. [Eg: BCT to Virar]
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MEMU or Main Line Electric Multiple Unit is a Local Train meant for Inter Town Travel within 1 State usually & has Toilet Facility. [Eg. Patna to Buxar]
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DEMU...
more... is Diesel Version of MEMU and runs on Non - Electrified Routes in States like Punjab and J & K ... :-)