Ground or earth in a main (AC power) electrical wiring system is a conductor that exists primarily to help protect against faults and which in normal operation does not carry current.
Neutral is a circuit conductor that may carry current in normal operation, and which is usually connected to earth. In-house wiring, it is the center tap connection of the secondary winding of the power company’s transformer.
In a polyphase or three-wire AC system. the neutral conductor is intended to have similar voltages to each of the other circuit conductors, and similar phase spacing. By this definition, a circuit must have at least three wires for one to serve as a neutral.
In the electrical trade, the conductor of a 2-wire circuit that is connected to the supply neutral point and earth ground is also referred to as the “neutral”. This is formally described in the United States and Canadian electrical codes as the “identified” circuit conductor.