The biggest difference between the economies of the North and South during the 1800s was the industrialization in the North and the agriculture in the South.
The North was much more focused on industrialization than agriculture. By this time they had cities and factories and had replaced slavery by using paid labor. Many people were living in cities and the North had more natural resources than the South to be able to keep this up. More immigrants would live in the North than in the South, which made sure to keep factories busy with jobs, and transportation was much easier as well.
In the South, it was primarily focused on agriculture. Many southerners had plantations where they would grow cash crops like cotton, indigo, and tobacco. The climate was perfect for continuously growing crops like these, and the soil was rich and full of nutrients, unlike the North. With all of this, Southerners relied on slaves to keep up the plantations and to earn them money. They did not have as much transportation as the North did, many people lived in rural areas, and kids did not spend as much time in school as in the North, and were often not as literate.