The main difference between "The Last of the Mohicans" book version by James Fenimore Cooper and "The Last of the Mohicans" movie version, generally speaking, is that the book has a more adventurous theme and the movie has a more love and romantic theme. Never the less, both stories were extremely interesting.
Main details that support this difference are that in the movie, Cora is supposed to wed with Heyward and Cora agreed with that. Then she met Hawkeye when he saved her from an ambush from the Hurons. From there they fell in love and Heyward was out of the picture as far as love is concerned. So, Cora is the one who is in love with Hawkeye and Alice takes the role of Cora. Another factor, dealing with the love theme differences is in the book, there was not a big love scene between Hawkeye and Alice as there was in the movie between Hawkeye and Cora. Thus making the movie a more romantic story. In the movie, key things that happen have different importance because the roles switch. For instance, towards the end of the book, Cora dies. In the movie, Alice dies. This is important because Alice and Cora have certain traits that make this more and/or less important to the story.
Differences in the between Heyward are that in the book, Heyward does not play as an important role as he did in the movie. In the movie, he sacrifices himself to the Hurons, in exchange for Hawkeye and Cora. The Hurons put him under a fire as a sacrifice and is tortured. He is only tortured for a short amount of time because as Hawkeye runs away with Cora, he shoots Heyward in the head putting him out of his misery and torture. Another difference in the movie from the book is that Heyward and Hawkeye disliked each other more in the movie than the book.
There are small but general differences between the book and the movie that are not really important but are differences, never the less. Such as, In the book, the main goal was to get everybody to the