So what is the difference between a Brown Bear, a Grizzly Bear, and a Kodiak Bear? A large part of it has to do with location. Brown Bears stick to the coastal areas, Grizzlies prefer inland habitats, and Kodiak Bears are native to a small chain of islands in Southern Alaska, where they have been isolated from the rest of the bear population since the last Ice Age. (12,000) years ago!)
There are also a physical differences - most noticeably, a hump! Grizzly have shoulder humps made up of fat and muscle that lend extra strength to their front legs, giving them a better ability to dig and swipe. Grizzlies also posses long, white-tipped guard hairs on their shoulders and backs that give them a "grizzled" appearance. Hence the name. There is also some pretty substantial sexual dimorphism going on with these guys, as the males can easily weigh double that of a female and be nearly 2 feet taller when standing on the hind legs.
Grizzly bears are omnivores, notoriously consuming whatever food is easily available to them. Salmon swimming to and from spawning areas are a popular meal, and the bears are also known to go after large prey such as Moose and Caribou. However, they also consume large amounts of plant material, including roots, which is where the digging skills come in.
Grizzlies are solitary animals. They mature sexually at around 5 years of age, and the males and female come together to breed in June or July. Females go in to hibernation and give birth, usually to twins, during the winter while hibernating. Mothers take excellent care of their young, who stay with them for about two years.
While the Grizzly Bear is found in only 2% of its original, native habitat down the the lower 48 states, the Alaskan population is thriving. 98% of America's Brown Bears (including Grizzlies) are found in Alaska, which also houses 70% of the overall North American population.