There’s a rugby World Cup going on right now, but it isn’t the Rugby World Cup. Not exactly.

The sport being played for the next month in Australia and New Zealand is known as rugby league. To an outsider, it may not look a whole lot different from rugby union, the more popular form of the game. In both kinds of rugby, large people without a lot of padding smash into one another while trying to touch down a ball at the end of the field.

But to aficionados, there is a world of difference. Fans of rugby league say the game is more exciting and free-flowing, while rugby union fans enjoy their sport’s traditions and emphasis on defense, kicking and physicality.

Rugby union is more familiar to people in the United States, where it is the primary form played at colleges. The rugby union World Cup gets its share of attention worldwide when it comes around every four years.

Rugby league, though it too is more than a century old, has spent much of its history trying to keep up with its more famous counterpart.