There were two main issues that caused splits between the delegates at the Constitutional Convention. One was slavery and the other was representation in Congress. Since the second part of your question asks about representation, I will assume that representation was the second major issue (and that slavery was the first major issue).
The issue of representation was about how many seats each state would have in Congress. The small states wanted all states to have equal representation in Congress. The big states wanted the seats in Congress to be divided up on the basis of each state’s population. This issue was solved through the “Great Compromise,” which is also called the “Connecticut Compromise.” In the Great Compromise, our current bicameral Congress was created. There was a Senate that would have equal representation for each state, the way the small states wanted. There was a House of Representatives that would be apportioned on the basis of population like the big states wanted. Thus, both the big and small states were at least somewhat satisfied, compromise was reached, and the states ratified the Constitution.