What is the difference between manual sewing machine and an electric sewing machine?

An electric sewing machine does it's work by using electricity to move the needle up and down, and rotate the bobbin.

The mechanical parts of a manual sewing machine, had to be set in motion by turning a handle, or pedal.

An electric sewing machine has an electric motor attached to these rotating parts, by belt or gearing and operated by a foot switch.

This makes it less tiring on the arms or feet, you can keep sewing faster and longer.