The changes were that the personality of each person changes. Like Stanley was good-hearted at the first place but then later in camp he was stiff/cold-hearted because of the way the counselors treat him and the hard work that he had to do. But he did have friends with him.

Bradley was different, he was lonely and a bully at school. But in the end he was friendly and tried to work hard on his studies, which is a thing that he never had done before.

My point is that the 2 characters' personalities changed throughout the story. Though they had hard times in the middle of the story. Bradley was nothing like Stanley in the first place, neither was at the end.