Neutral: It is the Star point formed in 3 phase balanced AC voltage or current system,having vectors of 120 electrical degrees apart in between the Phase values.In case of asymmetrical faults, the neutral shall shift and the condition of the Phase values of current or voltages being 120 electrical degrees apart will no longer be there.
Grounding: It is nothing but earthing the current carrying lead of equipment in case of earth faults to allow Zero sequence current, to the main earthing system or Earth mat of the S/s.
Earthing: A connection from the metallic portion/parts of the equipment to the S/S earthing system or Earth mat which would safe guard against damage to the Equipment/ Structures in the S/s and Human being against dangerous step and Touch potentials in the EHV s/s in particular.
Neutral conductor is the path for return current whereas Earth conductor is a low impedance path to earthing system for clearing fault currents (usually caused by insulation failure / mistakes)by causing the tripping devices to activate and Grounding conductor is for providing equipotential bonding for all metallic structures, irrespective of its connection to electric circuit, to prevent step voltage generally caused by high voltage surges like lightning. Grounding conductor is normally bare copper and connected to the facility’s grounding and lightning protection network.