What are the differences and similarities between the movie and book versions of Steinbeck's Of Mice and Men?

There are two feature length films of Steinbeck's novella Of Mice and Men. One was made in 1939 with Burgess Meredith and Lon Chaney Jr. It is an excellent adaptation but might not be as appealing to a modern audience as the 1992 version with Gary Sinise and John Malkovich. For that reason, I will focus on the 1992 version. 

The plot is basically the same and the most important scenes, the opening scene...

There are two feature length films of Steinbeck's novella Of Mice and Men. One was made in 1939 with Burgess Meredith and Lon Chaney Jr. It is an excellent adaptation but might not be as appealing to a modern audience as the 1992 version with Gary Sinise and John Malkovich. For that reason, I will focus on the 1992 version. 

The plot is basically the same and the most important scenes, the opening scene with George and Lennie camped by the Salinas River, the fight between Curley and Lennie, and the scene with Lennie and Curley's wife in the barn are virtually identical, even down to the dialogue. In fact, the dialogue is exact in many places including the dialect used by the characters.

There are, however, some differences and things that are left out. One major difference is that the story is told as a flashback as George rides on a train. Another big difference is in the portrayal of Curley's wife. There is a hint of attraction between George and Curley's wife which does not exist in the book. There is an added scene with George and Curley's wife alone in the barn. She also seems more vulnerable in an added scene where she cries about Curley breaking her record collection. A major scene which is left out is the beginning of chapter six when Lennie is talking to the imaginary rabbit and his dead Aunt Clara. Obviously, this scene may have proved difficult to film. The ending of that chapter when Curley, Carlson and Slim show up after George has shot Lennie is also gone. 

The actors seem as though they actually walked off the pages of Steinbeck's book. John Malkovich as Lennie and Ray Walston as Candy are particularly excellent and embody all of the characteristics of those men. The director did a great job of making Malkovich look as big as Lennie. There is an added scene, which fits perfectly, showing Lennie loading grain bags on a wagon. There are two such scenes of the men working in the fields which do not detract and are implicit in the text. The setting too is very realistic. Although the movie was not filmed in the Salinas Valley, it was filmed about 200 miles south in the Santa Ynez Valley of California, which, for all intents and purposes, is virtually the same. The bunkhouse too is a good replica down to the card table and "tin-shaded electric light."