The word plug implies cork or stopper. Plug top was invented in 1880’s and at that time it came with two pins only. Plug top is used to connect the wires from an appliance and then inserted in an electrical socket to make the connection for electricity supply.
On the other hand Multiplug is like a multi socket. Multiplug allows one than more plugs to connect to a single electrical sockets. These multiplugs contains similar multiple sockets. It helps multiple plug top to connect to the electricity.