A grizzly typically has a concave or dish-shaped profile that extends from between its eyes to the end of its nose. A black bear normally has a long, fairly straight profile from forehead to nose tip. The dished-face profile of the grizzly makes the face appear broader (when seen full front) than that of the black bear; the face and forehead of the black bear appears more round.
Grizzly Bear—Dish-shaped facial profile
Black Bear—Straight facial profile