The only difference I see is that the ice cube chairs on each side of the room are rotated exactly the same. Ice cubes have two "faces." To be an exact mirror image, either the left or right hand side cubes need to rotate one rotation. Difficult to explain, but check it out!
Edit: This does not count the cubes down the middle of the room. I'm talking about the five cubes that have a mirror double on the opposite side.