What is the difference between ground and neutral in an AC circuit?

Earth or earth in a network electrical cable system (AC power) is a conductor that provides a low impedance path to earth to prevent dangerous tensions from appearing in equipment (high voltage peaks). Neutral is a circuit conductor that normally completes the circuit back to the source.The ground in a mains electrical wiring system is a conductor that provides a low impedance path to the earth to prevent high voltages from appearing on equipment. Is this true? A neutral conductor completes a circuit back to the source.