Technically, they are one in the same, though distinct subspecies do exist. Brown bears found in the United States are commonly referred to as Grizzly Bears, whereas brown bears that make their home outside the U.S. are often known as simple brown bears. The North American Grizzly bear makes his home almost entirely in Alaska now, and most other subspecies of the brown bear that roamed the central portions of the United States are non-existent. The much larger Siberian brown bear weighs nearly 800 pounds, and is similar in size and weight to the North American Grizzly bear, also known as the common U.S. brown bear. This large, menacing animal has a prominent shoulder hump, small ears, and long, straight claws.
Brown bears range in color from dark brown through light blonde.
Because of their tremendous size, brown bears rarely climb anything, even as cubs. Surprisingly agile, however, brown bears can run as fast as 30 m.p.h. Grizzly bears carry a certain reputation for being dangerous, menacing animals. While it is true that brown bears have attacked humans for no apparent reason, most officials say cause for alarm is not necessary. They advise keeping a distance of 100 feet between the bear and you, and avoiding female bears with cubs altogether.