In the novel there is a main part about Johnny Fontane and his wifes and problems etc. Not in the film. There is also a part in the novel were Bonasera is in court which is not in the film. Also there is a part were Nazorine realizes that he has to go to Don Corleone to make sure Enzo can stay in America.
Don Michael Corleone: "My father is no different than any other powerful man."