Mesothelioma and lung cancer are both serious health conditions that affect the lungs. However, the key difference between the two lies in their origin. Mesothelioma is a rare form of cancer that affects the mesothelium, a thin layer of tissue that covers most internal organs. Lung cancer, on the other hand, begins in the lungs themselves and can spread to other parts of the body if not caught early. Is Mesothelioma a Type of Lung Cancer?