What is the difference between a single phase induction motor and a three phase induction motor?

The primary difference between the two is the physical size of the actual motor to do the same job. For instance, A 5HP 1-Phase pump would be approximately 5X the size of a 3-Phase pump of the same horsepower. Also the size of the wiring is smaller in the 3Phase compared to a single phase of the same horsepower. The reason you can achieve this is simply the efficiency of having 3 poles of power compared to one. Three phase power allows the motor to operate in a steadier wave form, where a single phase alternates with one waveform only. You can create three phase power from single phase using a "Phase converter". They are strictly used for motors only as they do not create a perfectly balanced three phase load, but is usually good enough to operate motors.