The book ends the same way as the movie. Except there is a small conversation with the ticket guy on the train about how is oskar going to carry such a heavy trunk especially since it will be dark when they get to their stop. Since it is dark though he won't need help carrying it eli will be able to walk
It's just the way the tone was some people got the vibe that Oskar was going to be the new Hakan but this isn't the case. It just wasn't made as clear what their relationship was at the end of the book as it was in the ending of the movie, although some people who only saw the movie still got the impression Oskar would be the new hakan.
Huge spoiler also:
eli is a boy. eli is short for elias. he was castrated when he was turned into a vampire.