The difference between phlebitis and venous thrombosis usually lies in their different symptoms, different etiologic factors, and different lesion sites. 1. Symptoms: Phlebitis usually has symptoms such as local redness and swelling, swelling and pain that increase when walking and decrease after lying down, and dark red skin, while venous thrombosis usually has symptoms such as difficulty in breathing, swelling of the lower limbs, and change in the color of the skin. 2. Different causes: Phlebitis is caused by inflammation of the veins, which usually leads to lesions of the valves of the veins, while venous thrombosis is caused by the fact that the blood in the veins is thicker than that in the arteries, which results in the slow flow of blood in the veins and leads to the emergence of venous thrombosis. 3. Different parts of the disease: Phlebitis occurs mostly in the limbs and the main symptoms are local redness, swelling and pain. On the other hand, venous thrombosis occurs in the veins of the lower limbs, abdominal veins, pulmonary veins, and so on. It is recommended that patients go to the hospital for examination in time after discomfort occurs, and treat the symptoms under the guidance of the doctor.