Fahrenheit 451 by Ray Bradbury is very much a story about book burning. In a sense, Captain Beatty and Granger are similar in that they both use fire to burn books. However, aside from this physical act (as well as both men being well-read), the similarities stop there. Beatty uses fire in order to suppress individuality and intelligence, while Granger does the exact opposite.

As part of his job, Beatty is tasked with setting fire to book collections and, in some cases, human beings. Though he has clearly read many books in his time, he now views them with disdain. While discussing the history of firemen with Montag, Beatty attempts to rationalize book burning:

A book is a loaded gun in the house next door. Burn it. Take the shot from the weapon. Breach man's mind. Who knows who might be the target of the well-read man? Me? I won't stomach them for a minute. And so when houses were finally fireproofed completely, all over the world (you were correct in your assumption the other night) there was no longer need of firemen for the old purposes. They were given the new job, as custodians of our peace of mind, the focus of our understandable and rightful dread of being inferior: official censors, judges, and executors. That's you, Montag, and that's me.

Here, Beatty makes his case for why books should be burned. "Take the shot from the weapon," he says; to him, books represent intelligence and individuality, which in turn leads to inequality, which he blames for all the sorrow in the previous world. For "everyone [to be] made equal," books must be burned.

On the other side of the equation, Granger is a man who burns books not to suppress intelligence but to protect it. After Montag stumbles into the woods following a narrow escape from the mechanical hound, he comes across a group of men warming up to a fire (this is the other way Granger uses it: for survival). When Montag laments the fact that he does not possess his books anymore, Granger explains that in order to save books, he and his friends become the books:

"All of us have photographic memories, but spend a lifetime learning how to block off the things that are really in there. Simmons here has worked on it for twenty years and now we've got the method down to where we can recall anything that's been read once. Would you like, someday, Montag, to read Plato's Republic?"
"Of course!"
"I am Plato's Republic. Like to read Marcus Aurelius? Mr. Simmons is Marcus."
. . . "We're book burners, too. We read the books and burnt them, afraid they'd be found."

In a bizarre twist of fate, Montag goes from one type of book-burning to another. However, this time, it is being done in order to protect knowledge rather than suppress it. Though one can imagine Granger would love nothing more than to stop burning books, he does so in order to protect himself. By committing them to memory, he and his friends take on the role of both book and author alike:

. . . this other fellow is Charles Darwin, and this one is Schopenhauer, and this one is Einstein, and this one here at my elbow is Mr. Albert Schweitzer, a very kind philosopher indeed.

He shows Montag—and indeed, the reader—that though physical copies of books may be destroyed, the knowledge, insight, and ideals they represent live on through the people who read them.

The two characters use fire in opposing ways.  Beatty, the captain of the 451 fire department, uses fire to destroy.  The firemen burn books and people's homes, and in the case of the woman who refused to leave her books, people.  Beatty said that fire is clean because it gets rid of something.  After Montag turns the fire on Beatty and kills him, he recalls that Beatty had told him, don't face a problem, burn it.  Fire was a way of covering up and destroying to Capt. Beatty.  Granger, the leader of the book people, used fire for warmth and to draw people together.  After Montag emerges from the river and follows the old railroad tracks, he sees, in the distance, a fire.  He knows at once that it is not a destroying fire, but a warming one.  Fire is an important symbol in "Fahrenheit 451" and Beatty and Granger show the two views of it.