In the movie, the older prisoners would bet on which one of the new prisoners would cry first. This was never in the book. It was added to the movie because it gives a level of humor that the viewers can see. It makes it seem that the prison life that Andy is going through is not that bad. It makes the viewers sympothize with him more and that makes them more incline to watch the movie.
The Warden Norton has Andy do his taxes for him, because Andy;s job before he was put into prison delt with business and numbers. In exchange for this favor, Warden Norton, gives Andy special treatment. However, in the movie, it shows that the warden has Andy keep a seperate set of books for him, which he stores in the wall. This was never in the book. This added a level of mystery and suspense to the movie.
Byron Hadley is the mean prisoner that everyone fears. In the movie, he is arrested and in the story, he dies of a heart attack. The most logical reason that they did not put him dying in the movie was to avoid the sadness of the viewers, that death brings. It is easier to just "arrest" a person then to kill there character off. Not killing him, allows them to have the flexable to bring him back for another movie, which we know was not made.
The movie, The Shawshank Redemption was very good. It showed what pisoners go through, even though it might not be realistic. It also shows the emotions that a person can go through when they are put into stressfull situations. Another emotion that is shown in the movie is fear. Of course, they are in prison which is scary enough, but its the individual interactions that show how a person handles fear.