Auschwitz was liberated by the Red Army. The Soviet general was so horrified at site that he has the Nazis in charge executed on the spot.
You are correct about what the Americans did, but the camp was somewhere in western Germany.
I am afraid I don't know much about the "camps" per se, in thier location.
I just remember seeing one in Holland when my dad was stationed there.
The Americans liberated Dachau (near Munich), in addition to other concentration camps in Germany. The Americans were so repulsed by what they saw at Dachau German SS guards were lined up and executed by a firing squad. Over 40 Germans were killed. General Patton was told to investigate the incident shortly after the war ended and deep six'd the inquiry ... no American soldiers were brought up on charges.
BTW, at that time Auschwitz was part of the German territory - border of occupied Poland (Generalgouvernement Polen) was further to the east.