Parts of Auschwitz I and II have been preserved as a museum.
Auschwitz and it was located in Nazi-Occupied Poland.
Auschwitz-Birkenau (the Auschwitz group of camps).
Auschwitz
Auschwitz Birkenau, it acts as an death camp but it's an extermination camp.
Auschwitz-Birkenau was a Nazi death camp during WWII. It was infamous for the fact that most people shipped there where executed.
Auschwitz (Oswiecim in polish)
Because it had no strategic importance
The German occupiers set-up labour, concentration and death camps in occupied Poland. The Nazi created the death camps of Auschwitz II (Auschwitz-Birkenau), Chełmno, Bełżec, Majdanek, Sobibór and Treblinka. The Nazi German also created many concentration camps such as Auschwitz I.
Auschwitz
The death camp was called "Auschwitz".
Oswiemcim, better known by its German name - Auschwitz.