What is the difference between an oxygen and a nasal cannula?

An oxygen tank contains pure oxygen that's used to assist people with breathing difficulties, whereas a nasal cannula is a device that's used to deliver supplemental oxygen to the nose and mouth. Patients who require oxygen therapy might use a nasal cannula to help them breathe more easily by increasing the amount of oxygen they inhale. The oxygen that's delivered through the nasal cannula is typically measured in liters per minute and the flow rate is determined by a physician or respiratory therapist based on the patient's specific needs.