Pleurisy and lung cancer are different in many aspects, such as the nature of the disease, clinical manifestations, treatment methods and so on. 1. The nature of pleurisy and lung cancer is very different, the former is a benign inflammatory disease caused by infection, and the latter is a malignant tumor disease whose etiology is still unknown. 2. In terms of clinical manifestations, pleurisy without pleural effusion usually presents symptoms such as severe chest pain and fever, while chest tightness and dyspnea will occur if the patient has pleural effusion. Early stage lung cancer usually has no symptoms, while middle and late stage lung cancer will have many symptoms such as cough, hemoptysis, chest pain, fever, panic, shortness of breath and so on. 3. Treatment methods, pleurisy is mostly treated with drugs to fight infection, while the treatment methods of lung cancer include surgery, drug treatment, radiotherapy and other local treatments.