What is the difference between earthing and grounding when should I use any of both?

Ground and earth is basically the same thing. Its all about providing the least path of resistance to the earth mass. Neutral is connecting the star point of three phase equipment out which serves as a return path for the flow of electricity.

Earthing means you connect the grounding system to the real ground of the earth.

Grounding means you connect the device to the grounding system. Grounding system sometimes floating, or sometimes really earthed or sometimes connected to somewhere.

Earthing is normally Connecting a System with the Earth through a Conductor / Wire.

Earthing is done for Neutral Wire, Electrical Circuits, Electrical Devices, Lightening Protection, Fault Protection etc.

Grounding is normally Earthing of Neutral Wire if required.

Bonding is also a related term used for inter-connecting different Electrical Equipment to ensure Earthing through different Paths.