In any case all large carnivores are rare by nature and they require special attention. The two species have different life strategies. Wolves have a high reproductive potential. They can breed at one year of age and the average number of pups is five, although if population density is low and there is abundance of food they can have give birth to up to ten young. Really its biggest problem is the harm it causes to humans.
Bears have a very different vital strategy.
They do not really have natural enemies. Their reproductive rate is very low. It is a specialist species which must live in a given habitat, feeding on particular types of food, at least as far as Spanish bears are concerned. They are fairly incompatible with humans and the cannot inhabit populated areas. Therefore although wolves have found the means to boost their numbers given the smaller human persecution and their own capacity overcome adverse conditions, bears have not been able to keep their population up.