In a fight between two healthy, mature male bears, one of whom is a grizzly and the other a brown bear, the brown bear would probably win. An average brown bear is considerably heavier than a grizzly.
Brown bears and grizzlies are essentially the same species of bear. However, an adult male grizzly bear usually weighs between 400 and 790 pounds, while adult male brown bears can weigh up to 1,500 pounds. Both types of bears can stand over 9 feet tall. Brown bears have a shoulder hump that allows them to accelerate with ease as they chase after prey, making them the heavier, faster and more agile of the two bears.