How do white blood cells differ from red blood cells?

Red blood cells have a biconcave shape and an absence of a nucleus in order to increase the area for which it can carry oxygen around the body and remove carbon dioxide from the body. Red blood cells contain a protein called haemoglobin, which helps carry the o2 and gives them the red colouring. They are part of the cardiovascular system. White blood cells, however, work as part of the immune system. They do contain a nucleus, they are also larger, and they work to fight illness and disease. They are the defence mechanism against foreign bodies. They attack and destroy the pathogen on entering the body, there are two main types: phagocytes/macrophages and lymphocytes. They are part of the lymphatic system. They are both produced in the bone marrow.