This photo comes from my now deceased great uncle who served in Europe, I believe as a Chaplain's Assistant: View attachment 22136 The note on the back only gives the location and date: Versailles - Sept 24, 1945. No idea what the unit is or who any of the people in the photo are.
This is the main entrance of the Chateau de Versailles in front of the statue of Louis XIV. Your Grand father and his comrades were visting the Chateau with other Americans on leave. The two ladies are probably French translators:guides for the army.
the 1945 picture was taken just in front of the golden gate, this is why you don't see the statue on the first picture. When moving back you can see the exact place where it was taken, probably uopn getting off the bus. more here : http://paris1972-versailles2003.com/2010/12/21/chateau-de-versailles-2/#jp-carousel-908