Can someone help me with the answer?
Store and forward switches receive an entire packet before they begin sending any data at all. Cut through switches can receive the first few bytes of a packet, decide which port(s) to send it on, and then start sending out the packet while the rest of the packet is still being received.
Cut through switching only works if both ports are operating at the same speed. Cut through switching only works if the output port(s) happen to be available while a packet is being received.