Wehrmacht (國防軍) - the unified armed forces of Nazi Germany from 1935 to 1945.
It consisted of the Heer (army), the Kriegsmarine (navy) and the Luftwaffe (air force).
Waffen-SS (黨衛軍) was coexistence with Wehrmacht (not the 4th branch of Wehrmacht). Waffen-SS & Wehrmacht worked together in various combat situations.
Afrika Korps - German Africa Corps (Deutsches Afrikakorps, DAK): German expeditionary force in Africa during the North African Campaign of World War II (from March 1941 to May 1943). The best known commander was Field Marshal Erwin Rommel.