A snail letter will stop at many different postal stations and is rerouted until it finally reaches your mailbox. This can take anywhere from 2 days to 2 weeks depending on where in the world the final destination is.
Email passes from one computer to another as it travels along a network.
Each computer reads the email address then routes it to another computer until it finally reaches your electronic mailbox where it sits until you down load it. This usually takes only a matter of a few minutes regardless of where in the world the final destination is.