What is the difference between the way Candy sees himself and the way that Curley's wife sees him?

 Sadly there is not too much difference. Candy sees himself like his old and broken dog. He thinks he is expendable and useless to the Ranch. Curley's wife pretty much says the same thing to Candy. Candy, however, sees Curley's wife as a pathetic lonely predator who makes trouble for guys on the ranch.