I imagine that the Booker was making a bid toward being the biggest book award in the world when they finally, after almost 50 years, decided to allow novels from the most heavily populated English-speaking country in the world to be considered. I suppose that the average American has never heard of it.
But they will have heard of the Pulitzer. The Pulitzer is certainly the biggest prize in journalism, and it is primarily a journalism award. The Pulitzer for Fiction is determined by newspaper people (editors, owners, columnists, etc.) This is fine for actual journalism, not so good for Fiction. The process works like this. A jury of writers, critics, and other fiction types go through and pick a list of three books that they think are the best fiction of the year (usually novels). They then submit them to the newspaper board, who decides to whom they wish to give the prize. As a consequence, the books selected for the Pulitzer tend to be pretty conservative choices (Gone With the Wind, The Yearling, The Caine Mutiny). Faulkner did not win for The Sound and the Fury, As I Lay Dying, or Absalom, Absalom. He won for A Fable and The Reivers, two late works that are uncharacteristically conservatively written and not thought to be among his best works. Hemingway did not win for The Sun Also Rises or For Whom the Bell Tolls. He won for The Old Man and the Sea, long after his formalist innovations had become the new standard for writing. In 1974, the jury only submitted Gravity's Rainbow because they thought no other book published that year came close. As a consequence, the newspaper board decided to give no award at all. I'm always interested in what wins the Pulitzer, but I rarely read them. The last Pulitzer winner I read was The Goldfinch, a hugely entertaining novel, but not, in my opinion, high art. (What do we call a novel like this that is certainly not genre fiction, but not exactly literary?)
Competing for our attention is the National Book Award, which is awarded by the booksellers. Oddly enough, this award is frequently given to less commercial novels than the Pulitzer. (One might imagine that the booksellers would want to excite interest in books with broad popular appeal.) Among the first-rate novels (IMO) that won the National Book Award but not the Pulitzer are Gravity's Rainbow, JR (Gaddis), White Noise, and The Corrections. Not that they don't miss a lot, too. You can easily find the winners and the nominees online. Sometimes, it's almost embarrassing what they picked over what they ignored with ALL the prizes.
The National Book Critics Circle Award, chosen by, you guessed it, critics, is closest to an American equivalent to the Booker. They give the award to the best fiction published in English. They'll even give it to a translation. (2666 by Bolaņo won in English translation!) They have often awarded it to non-Americans. I find it the most interesting of the American awards, but of course I don't always agree with their choices.
I've never paid any attention to the PEN/Faulkner award. I don't know much about them. I have no idea how the French look at English language awards. I suppose that most people are primarily interested in ones that have been translated into French, although I know there are many more bilingual (or multi-lingual) people in France than in the US (or Britain, I think). Fully 40% of the Prix Goncourt winners don't seem to have ever been translated into English.
Out of curiosity, I tallied what I had actually read from each award and then did a percentage since the awards have been around for different lengths of time.
Pulitzer - 16 (16% of winners)
NBA - 19 (27%)
NBCC - 13 (30%)
PEN/Faulkner - 4 (10%)
Booker - 7 (14%)
Prix Goncourt -3 (4% of books translated into English)