These two terms are generally used interchangeably. Scientifically, the term ‘pulmonary’ is used for lungs, (with its collective part), and functions. On the other hand, the word ‘respiratory’ is used only for indicating the movement of air in and out of the lungs along with the transportation of oxygen and carbon dioxide through the lungs and blood. These two words, however, pretty much defines the same function of the lungs.