Big difference in Blacks vs Grizz in my experience...but just about all of them want nothing to do with you unless you have an animal down.
My buddy Kirk and I were hunting SW Co OTC archery elk one year and since it so heavily hunted we would get out very early4 am -in the woods. We were bushwhacking through some dry aspens in the dark and we hear an animal following us- (no firearm on either of us)...its a mangy bear, must have smelled the PBJ's in our packs.
We stopped and he literally walked right up to us, about a 120# brown phase Blackie so I kicked him hard in the snout with the heel of my boot and he ran off.
I was bluff charged one night by a black bear with 2 Cubs, I held my bow above my head and spoke to her when she stopped, popping her teeth at me. She woofed them out of the tree and walked away. I'm glad she did, I was over 2 miles from my truck. 99% of blackies I've seen ran the other way, fast.
Ive bumped a bunch of black bears in Mass and NH they take off real quick. The only time I got nervous was when I got in between a sow and her 3 Cubs during a turkey hunt. She was huffing and snapping her jaw at me at about 15 yards. My throat got real dry real quick. I backed up a few yards and they slowly went on there way. That made for an interesting day.
I was hiking down a trail and noticed some fresh dirt and thought that was odd. Looked to the right and saw a yellow jackets nest and that's when the oh shit light went off. I drew my pistol at the same time I looked up and saw a black bear charging down hill at me. Gave it a "Hey Bear" and it put on a full stop 25-30 yards away. I kept talking to it while I slowly moved on down the trail.