When I first opened this thread, I was confused for a minute, as the OP asked if it was a grizzly or brown bear, but the pictures were of a Black Bear. I was like, huh? And as others have said, a brown bear is a grizzly and a grizzly a brown bear, just called by a different name based on location.
That's a nice black bear. I think I know what I'm talking about since I've seen quite a few of all species, and am sitting here typing this in my game room, which has a couple brown bears, a mountain grizzly and black bear all in it, all within 30' of me as I type this. The guys who think that's a grizzly need to take a bear identification class.