Most bears in lower 48 are black bears (not necessarily black)

Actually color does not necessarily tell you whether it's black bear or grizzily, as grizzilies can get dark color and black bear can be brownish.

The big hump on the back is usually the tell-tale of a grizzily.

Colors of bears are usually affected by the food they eat. Bears are not big meat eaters and their diet is mostly vegetarian, berries, ants, and occasionaly rats and little animals such as bunnies. Most bears don't attack humans for food. They attack when they feel they or their young are threatened. That's one reason why a surprised bear is dangerous.

Once bears eat human food (including those in the dumpsters), they are more likely to go after humans. So in bear country, it's extremely important to store food properly and throw away trash in bear safe dumpsters.