BOSTON — There's a difference between the Masters and the Southern Farm Bureau Classic, between the French Open and the country club championship, between the Kentucky Derby and the eighth race at Aqueduct.

For marathoners, there have always been courses that stood out for their prestige, their tradition, and their purse. Starting in Boston today, those races are now the World Marathon Majors.

"The whole point is to be the best runner in the world," Olympic silver medalist Meb Keflezighi said as he prepared to make his debut in the Boston Marathon and try to take the early lead in a two-year competition for bragging rights — and a $500,000 bonus.

Joining marathons in London, Berlin, New York, Chicago and Boston, the World Marathon Majors will award points and $1 million in prize money to the world's top man and woman at the 26.2-mile distance over two years.

"Monday is the start of two races," New York City Marathon director Mary Wittenberg said. "One of the races will be over in 2 1/2 hours. The other race — to be the world's greatest marathoner — won't be over for 18 months."

Marathons have a devoted but — compared to leagues like the NFL — relatively small following that keeps the sport from reaping billion-dollar TV deals and more lucrative licensing fees. The splintered structure also leaves the races competing for runners and attention.

So the five races looked to the mainstream sports for a system that will reward athletes for long-term consistency instead of just one day of greatness. The circuit also creates other marketing and promotional opportunities that weren't available to them when they were just a bunch of different races.

"We feel like we're at a different level, and we felt we have an obligation to bring the sport into the future," Boston director Guy Morse said.

In coming up with a point system, organizers of the marathons looked to the grand slams and Triple Crowns in other sports to see how it was done. Of special interest was NASCAR's new Chase for the Championship, which made a mini-circuit out of a yearlong season.

"Our attention ebbs and tides," Chicago executive race director Carey Pinkowski said. "We looked to the mainstream sports and how they stay in front of the audience."

But while horses can run three times in five weeks and cars every weekend, humans usually run no more than two marathons a year — one in the spring and one in the fall.

Organizers knew two races weren't enough to crown a true champion, so they came up with a two-year cycle, overlapping so that a bonus will be awarded each fall starting in 2007. Runners get 25 points for winning a race, decreasing to 15, 10, 5 and 1 point for fifth place.

"Everything is influenced by the fact that the athletes can't — and we don't want to encourage them to — run more," Morse said.

For now, the marathons will fund the bonuses themselves. A title sponsor — and a $1 million top prize — is likely soon.

Among the other changes being discussed are a uniform system that will make it easier to identify individual runners, instead of their shoe sponsors. Organizers are talking about a system that would allow competitors to carry their bib numbers from race to race to make them recognizable and marketable by number, like Mia Hamm's No. 9 or Dale Earnhardt's No. 3.

Olympic gold medalist Stefano Baldini would wear a gold jersey, and world record holder Paul Tergat would wear yellow, like the leader does in the Tour de France.