Chemotherapy and radiotherapy for bladder cancer differ in principle and scope of action. 1. Principle: Chemotherapy for bladder cancer is chemotherapy, the main principle of which is that chemical drugs are injected into the body through vein or perfusion to eliminate cancer cells. Radiotherapy for bladder cancer is physical therapy, the main principle of which is that gamma rays or X-rays and other substances carry out radioactive treatment on local tumors to achieve the purpose of inhibiting and destroying cancer cells. 2. Scope of action: chemotherapy for bladder cancer can be injected intravenously to achieve the purpose of systemic treatment. Radiotherapy for bladder cancer belongs to localized treatment through rays. Bladder cancer patients should choose radiotherapy and chemotherapy under the guidance of doctors.