A high-pitched whistling sound when you breathe is the first tip-off that air is fighting to make its way into or out of your lungs. That sound is aptly named wheezing, and it is something that people with lung conditions—like asthma and chronic obstructive pulmonary disease (COPD)—have to deal with on a regular basis. But how can you tell which is to blame for your labored breathing? Asthma and COPD sound similar, but they have fundamental differences when it comes to symptoms, causes, and treatment—here’s everything you need to know.What is asthma?Asthma is a chronic lung disease and symptoms can range from mild to life-threatening, according to the American Lung Association. With asthma, the two bronchial tubes responsible for carrying air into and out of your lungs are inflamed and narrowed. When something like pet dander, pollen, dust mites, or mold triggers your asthma symptoms, these airways become even more swollen, and the muscles surrounding them constrict and spasm. No surprise, this makes it difficult to breathe. Because there isn’t a cure, treatment is focused on keeping symptoms under control so they don’t severely impact a person’s quality of life.What is COPD?COPD, the umbrella term for a group of conditions—emphysema and chronic bronchitis, among them—causes airflow blockage and breathing-related problems, per the Centers for Disease Control and Prevention (CDC).Similar to asthma, with chronic bronchitis, the bronchial tubes become inflamed, but for different reasons. Instead of, say, Fluffy the cat triggering inflammation, it’s most often due to long-term exposure to things like smoke. Other defining features of chronic bronchitis include a cough that you just can’t get rid of and excessive mucus, according to the U.S. Library of Medicine.Emphysema, which often goes hand-in-hand with chronic bronchitis, destroys the air sacs at the end of the tiny air passages in the lungs. This, too, is the result of exposure to cigarette smoke and other irritating particles or gasses, according to the Mayo Clinic.So, what is the main difference between asthma and COPD?There’s, unfortunately, no way to prevent asthma, but that’s not the case with COPD. For 85 to 90% of people with COPD, cigarette smoking is the culprit.“COPD is very much linked to a history of smoking, whereas asthma is not,” Neeta Ogden, M.D., an asthma specialist and immunologist in New York City, and a member of the Medical Scientific Council of Asthma and Allergy Foundation of America, tells SELF. “People with asthma will often say they have never touched a cigarette and avoid smoke as much as possible.”With that said, long-term exposure to other lung irritants like chemical fumes and air pollution also play a role in COPD, according to the American Lung Association.Another big difference: Chronic bronchitis, a type of COPD, classically presents with a chronic cough that lasts for months, which isn’t always the case with asthma, Dr. Ogden says. If you’re still not sure which one you’re dealing with, ask yourself this: Do you experience wheezing and chest tightness more at night? Or do you also deal with allergies, like hay fever, or eczema? Then asthma is likely your answer, per National Jewish Health.