Despite having the same characters and much the same story, the two versions are completely different in feel and in their respective endings.
Some say that the movie version sanitises Holly Golightly, who’s basically a working girl, damaged and unfathomable. And whereas by the end of the movie, Holly surrenders to love, in the novel she moves on, leaving the unnamed narrator searching for faint clues as to her whereabouts.
But both versions work for me. One Holly leaves, and the other Holly stays.
And both of them break my heart.