What social, cultural, and geographic factors divided and/or differentiated colonists prior to the 1770s? Pay close attention to regional differences, security, economic differences, and social demographics. Implicit in this question is the idea that the 13 colonies themselves were different from one another, and that forming a union in the 1770s might pose some difficulties.
There were a number of factors that made the colonists very different from one another before the 1770s. These differences were significant enough that it was very hard to make the colonists think of the 13 colonies as a group of states that should be united, rather than as a set of potential independent countries.
The major importance of geography had to do with distance. The various colonies were spread out across a long coastline. In those days, travel between the various colonies was difficult. Distances that now seem short were then very significant. Therefore, people from one colony might see people from other colonies (particularly those that were farther away) only very rarely. This made them more likely to see themselves as different from one another.
Perhaps the most important factor of all was economic. The various regions had economies that were rather different. The New England colonies were not great for agriculture and therefore had more diversified economies that relied heavily on the sea. The middle colonies like New York could be called the breadbasket of the colonies. They grew things like wheat and other grains and sold to other colonies on the continent and in the Caribbean, but they did so largely on individual small farms, not on plantations. The South, of course, was made up of plantations growing crops like tobacco, mainly for export. Importantly, these crops were grown by unfree labor—indentured servants and then African slaves.
There were also cultural differences, some of which came out of the economic differences. The cultural and social differences were partly due to religion. The New Englanders were Puritans. There was a mix of religions (and ethnicities) in the middle colonies. The South was largely English (and African) and was strongly Anglican. The South was also much more of a feudal society, dominated by the planters, while the middle and northern colonies were more egalitarian.
All of these factors combined to make the various colonies, or at least the various regions, seem like very different places that would have a hard time uniting.