differences

They don't show or even mention anything about the mechanical hound in the movie and it is a big thing in the book.

Also Clarisse doesn't die, Faber doesn't even show up in the movie, and I think Clarisse kind of takes over that role in the film.

AND the city doesn't get bombed in the end of the movie, whereas in the novel, Montag sees Mildred die when the city is bombed.

Here's the wikipedia link:

http://en.wikipedia.org/wiki/Fahrenheit_451

Hope that helps

no