Ozone depletion occurs in the ozone layer.

Ozone depletion is the process where ozone holes are created in the ozone layer. It is caused due to the action of chloro-floro-carbons on the ozone molecule to break it down to oxygen.

Ozone layer hole is the low concentration of ozone. It is present in both hemisphere.

Ozone layer is present in the stratospheric region of atmosphere. It is a pool of ozone molecules.

The ozone depleting chemicals are CFC's. They react with ozone and deplete it.