Cowboy, you are correct that you can't exactly call species simply on hitting a tent. That being said, when you have an unprovoked, tent related fatality and both species are present, it tends to go towards a black bear.---I will say, the Yellowstone area tends to throw a kink in this trend. Yellowstone area grizzlies probably about the most human conditioned grizzlies out there, so they have some behavioral stuff that is occasionally slightly different.
There are some details that apparently aren't released yet that could make it pretty fast to determine the species.