Corrosion: Corrosion is the process of slowly eating up metals by gas and water vapours present in the atmosphere due to the formation of certain compounds like oxide, sulphides, carbonate, etc.
Rust:
Corrosion of iron is known as rusting.
Rust is the hydrated Ferric oxide with having chemical formula .
When Iron comes in contact with oxygen in presence of moisture(Water), a reddish-brown coating is formed on the surface of Iron which is called rust.