Compared to a black bear's tracks, grizzly tracks of the front feet are more square. If you take a straight edge and hold it across the track of a grizzly front foot, just in front of the pad and behind the toe on either side, it will not cross the toe on the other side of the foot. A black bear front track is more rounded and a straight edge will cross the toe on the other side of the foot.

Grizzly bear tracks

Black Bear tracks

Grizzly Bear tracks

Black Bear tracks