When the chief compared himself with McMurphy, how did he feel they were different?

The Chief wondered how McMurphy could be what he is. He wondered how " a man that looked like that could paint pictures or write letters to people...McMurphy hadn't let what he looked like run his life one way or the other." The Chief stares into the mirror and reflects how his own physical appearance forms everything that he does; Unlike McMurphy, there is no mystery behind him.