Distinguish between ozone and ozone layer?

Ozone is a molecule, with certain chemical properties, a propensity for absorbing UV-B or more energetic radiation, and is unstable... tending to decay back to oxygen.

The ozone layer is a region of atmosphere, with the usual 70+% of nitrogen and 20+%oxygen, and the usual trace gases. Only the amount of ozone present increases to ~9 ppm (peak) in the lower stratosphere.