What is the difference between a nebulizer and compressor?

A nebulizer is a device commonly used to administer medication in the form of a mist that is inhaled into the lungs.  The most commonly used nebulizers are called Jet nebulizers.  Jet nebulizers are connected by a piece of tubing to a compressor. 

compressor is the device that drives the nebulizer.  It compresses room air and blasts it at a high speed through a liquid medicine to turn it into a mist of fine droplets which is then inhaled by the individual.