Earthing and Grounding are two different simple concepts which people often gets confused. Let me explain both of these things in simpler manner.
*.Earthing means connecting the dead part (it means the part which does not carries current under normal condition) to the earth. For example electrical equipment’s frames, enclosures, supports etc.
Whilegroundingmeans connecting the live part (it means the part which carries current under normal condition) to the earth. For example neutral of power transformer.
*.The purpose ofearthingis to minimize risk of receiving an electric shock if touching metal parts when a fault is present.
While the purpose ofgroundingis the protections of power system equipment and to provide an effective return path from the machine to the power source. For example grounding of neutral point of a star connected transformer.
*.Groundis a source for unwanted currents and also as a return path for main current some times. Whileearthingis done not for return path but only for protection of delicate equipments.