The major contrast between these two models of the frontier is that the Spanish “frontier” was tightly controlled by the Spanish government whereas the American frontier was more of a place where individuals could be independent and could get ahead on their own initiative.
The Spanish border areas were dominated by the Church and the state. They were there to protect the Indians and to convert them to Christianity. This created a frontier in which there was very little individual initiative. The frontier the Spanish created was not one where pioneers of the American sort could thrive. This is in contrast, Weber says, to the American system where individuals went out on their own and their energy transformed the frontier.
Of course, this was not all bad. It was certainly more benevolent (if more patronizing and patriarchal) towards the Native Americans. But it still created a much less dynamic frontier model than the American system did.