The difference between pneumonia and lung cancer usually lies in the causes and symptoms, treatment modalities, different images, and so on. 1. Causes and symptoms: Pneumonia is caused by bacterial and viral infections, and at the onset of the disease, symptoms such as fever, cough and sputum usually appear. The cause of lung cancer is unknown, and it is related to factors such as serious environmental pollution and smoking, etc. Lung cancer has no obvious symptoms in the early stage of its development, but in the later stage, it will have symptoms such as chest pain, hemoptysis, dry cough and emaciation. 2. Treatment: Although both pneumonia and lung cancer occur in the lungs, pneumonia can be cured by medicine, while lung cancer cannot. Pneumonia can be treated with amoxicillin, acyclovir and other medicines under doctor’s guidance, while lung cancer can be treated mainly by surgery, combined with radiotherapy, chemotherapy, targeted therapy and other methods when necessary. 3. Imaging difference: pneumonia is mostly flaky shadow with clear boundary, lobar pneumonia is mostly distributed in lobe segments, lobular pneumonia is mostly distributed along bronchial tubes. Lung cancer is characterized by mass shadow with unclear boundary and burr at the edge, which may be accompanied by eccentric sound and cavities. It is recommended to stay away from oil and smoke, actively exercise, quit smoking and drinking, keep optimistic mentality, and go to the hospital for examination timely if any uncomfortable symptoms, and carry out treatment under the guidance of doctors.