Distinguish between

Face-centred and end-centred unit cells.

Face-centered

End- centered

An fcc refers to a crystal structure consisting of an atom at each cube corner and an atom in the center of each cube face.

An ecc refers to a crystal structure consisting of an atom at each cube corner and an atom in the center of any two opposite faces.

Examples: tungsten, chromium.

Examples: Gold, silver, copper, nickel, etc.