Phlegm and snot are not the same thing, both are secretions, but both have different sources and different ways of discharge. 1. Phlegm is the secretion of the respiratory tract, which is mainly located in the bronchial tubes, trachea, pharynx and other mucous membrane surfaces, discharged by coughing. 2. Nasal mucus is the secretion of the nasal cavity, which is mainly located in the nasal cavity and nasopharynx, and can be discharged by blowing the nose, or can be discharged on its own. The reasons for the formation of phlegm and snot are related to bacterial and viral infections as well as physical and chemical factors. The color of phlegm can be white, yellow or brick red. Nasal mucus can be clear or yellowish pus. If the patient has more nasal mucus or sputum, which lasts for a longer period of time, he should go to the hospital in time to clarify the cause of the disease, so as to avoid delaying the condition and causing adverse consequences.