Grizzly and black bears are two TOTALLY different beasts, but with many similarities. Both are omnivores, both will actually avoid humans if they hear you first, and you don't want to get between either type of mama bear and her cubs. The grizzly is much more territorial than black bears (in general) and is more prone to go on the offensive if surprised.
I've encountered a few black bears in the High Peaks of the Adirondack Mountains over the years. All incidents occurred when humans weren't taking care of food properly (not me or the guys I hike with) and all incidents concluded with nothing but property damage (and rightfully so, silly people.)
I did love how that bear just kind of looked up like he was saying, "Oh, excuse me, my mistake, I thought this was a different tree stand. Could you give me directions to the berry patch? So sorry to have troubled you..."