As the story progresses, many youngsters inevitably die in the Hunger Games. In the book, some of these deaths are prolonged, showing the perseverance some of these characters have in their final moments. For instance, in an early scene, Katniss makes camp near a young woman who starts a campfire. After the young woman is discovered, she is attacked and nearly killed by some of her fellow tributes. But when they discover that she's alive after the attack, Peeta is sent to finish the job. In the conclusion of the book, Cato - facing off against a group of mutant mutts - survives for several hours before Katniss puts him out of his misery.
In the movie, however, these deaths are done quickly. It's possible that the deaths are abbreviated in order for the film to earn its PG-13 rating. But regardless, the film finds the bonfire girl dying quickly after she's attacked and Cato only suffering a few moments before Katniss ends his life.