My chance at pedantry! Also, some black bears are brown, and some grizzlies are black. If you live in overlapping territory, it may be easier to know them by shape... but if you're close enough to discern shape, you're already in a bad spot.
Ooh bear facts! My favorite bear fact is that there is no grizzly bear species. Sure, there's regional genetic variation, but they are all genetically brown bears.
What they are named for is the grey hairs on their pelt, which are caused by the stress of malnutrition. This is why they are so much more aggressive than the other bears: they are literally starving because there is not enough calories in their environment to keep so many land sharks happy and healthy.
Maybe, but really when you are in bear territory, and close to areas where bear congregate (rivers being one), just a few loud claps and a couple of loud "HEYS" is good enough to flush most bears.