There's a difference in the meaning

The contrasts between the novel and the film are evident in that the film is able to show the qualities that make noir what it is. The novel hinders those effects because it’s hard to show shadows lets say through words. Those who are unfamiliar to noir wouldn’t be able to understand the elements that are in noir by just reading the book. They would have to see the movie in order to get it. In the book the ending is some far fetched to me. To murder and then to have Keyes send them off on a cruise isn’t the way these things happen. The film has a more believable ending. A price must be paid when a life is taken, not a reward given. Justice was served in a more appropriate way in the film. The significance of the man on crutches is an illustration of the main idea of the film. Mr. Dietrichson is on crutches when his murder takes place with Walter presenting himself on crutches in order to show that Dietrichson was on the train when in fact he wasn’t. It’s the one clue that was used to take the switch of who is who. With the name of the film being Double Indemnity and the insurance connection, it all symbolizes the meaning of the movie.