The North and South were very different in a lot of ways, the economy was different, the people, and the land. These differences continued over time and soon created a gap between the North and the South, where it was hard for them to agree on things or get along.
In the North, they focused on industrialization. There were many factors that contributed to this. The climate in the North was not good for agriculture, it was cold and had rocky soil, so it was hard to grow crops. There was also an abundance of natural resources like iron and coal, which would contribute to industrialization further with the creation of railroads. Railroads made it easier to ship items, people, and resources back and forth, which eventually would make for industries to be the main source of profit, as the items being made were so easy to distribute and many people would take these industry jobs.
In the South, they focused on agriculture. There were many factors that contributed to this as well. The climate in the South was great for agriculture, it was warm and had fertile soil. The South also had a lot of land, as there weren't many cities or towns and people were very spread out. They would focus on growing cash crops such as rice and indigo, later turning to cotton. The South would sell these crops overseas, which was their main source of income. First, they used indentured servants to help out on the plantations, but they realized this was not the most efficient way. This would cause them to turn to slavery, which ended up rapidly increasing since it was earning them a lot of money.
The North did not depend on slavery, as they had industries with people who got paid and were not enslaved. Many people in the North did not agree with slavery and thought it was immoral, but the South thought different. They did not see these slaves as people and relied on them in order to maintain their plantations and earn a profit.