Despite his size a bear is an ineffective killer, where the lion is a very effective killer. This can be explained by the fact that the omnivorous bear does not need to kill all his food but the lion does. People who are attacked by bears often survive, people attacked by lions seldom survive, if that is any sort of measure. Bears can be quick, but not so quick as a cat. The bear would be more resilient to injury, but the lion would be better at inflicting injury and in the end I believe that would win the day. The result must remain conjecture because any sort of contest would be artificial leaning the advantage to one animal or the other, and I for one would not care to see it.