While the major themes of anarchy and anti-consumerism are largely prevalent in both mediums, there are similarities and diversions from the source material.

Enjoy.A cultural phenomenon, Fight Club, has remained iconic since its release in 1999-and yet, the original novel by Chuck Palahniuk seems largely uncelebrated despite the three-year difference in publication. However, the adjustments to the main heroes’s characters and the addition of several touching moments change the book into a heart breaking movie. All these changes have been made to make the movie more touching. So basically, the director chooses a different ending because he changed the character's personality and in order to maintain consistency in this, it's not just the ending that has been changed, as you read the book you should know better than me: some scenes were added, some of them were cut off. This change certainly changes the viewer’s perspective on Jenny’s personality. The viewer of Forrest Gump doesn’t know her real feelings and might even think that the main character is the person to whom she runs for a comfort and a place to stay until she is strong enough to run away again. However, his mental impairment doesn’t seem to bother Jenny, the love of Forrest’s life, who’s feelings toward Forrest evolve differently in the movie compare to the book. In the movie Robert Zemeckis decides to change that and makes her more confident in her son’s mental skills. “How you gonna have a plan, Forrest?.You is a idiot. In the book, however, it seems as if Forrest’s mother doesn’t take him more than just an idiot. Jenny, and Forrest’s mother are the only two people that love Forrest the way he is. Also he is described as a big, tall, and a really strong person while in the movie the viewer would describe him as an average man. This significant changes play an important role in the viewer’s perspective of Forrest.

Robert Zemeckis, director of Forrest Gump, chooses not to include several adventures that are present in the book and to change the character’s personality. I'll quote some of them, that should answer your question: I found a very interesting article based on the differences between movie and the novel.

Book forrest gump is based on