This is rather a broad question, as there can be several aspect of the “nature” of Spanish colonization. Let us look at a few of the important aspects of this colonization.
First, this colonization was undertaken by a relatively few Spaniards. In contrast to the British to the north, the Spanish did not come to the New World in large numbers. Instead, there was a rather small group of elites of European descent at the top of Spanish colonial society.
Second, Spanish colonies were a “frontier of inclusion.” Since so few Spaniards came over, Spanish colonies had large numbers of native peoples. They soon came also to have large numbers of mixed race mestizos. This was in stark contrast to the British colonies in which there was little mixing with the native peoples and natives were typically driven away rather than becoming part of white society.
Finally, Spanish colonies were much less democratic and egalitarian than the British colonies. The Spanish colonies were centered around Spanish owners of huge estates. These people became something of an aristocracy. This led to a society that was very different than the society of middle class whites in the British colonies.
These are some of the most important aspects of the nature of Spanish colonization in North America.