There are quite a few major differences between the North and the South at the beginning of the Civil War. These differences were economic, political, and geographic in nature and were major factors in the coming war.

The South was largely an agricultural nation, focusing on growing and cultivating crops. The North, on the other hand, was much more industrialized, with factories to produce industrial technology and machinery.

In terms of politics, the South favored the states’ rights, which is why they held fast to the issue of slavery, believing the Federal government should not intervene in the States’ decision making in regards to their rights. The North was more comfortable with a powerful federal government and focused less on states’ rights.

Geographically, the South was a much larger area, encompassing about twice as much land as the North. This actually was detrimental to the South, because they had to have much longer supply lines and transportation to reach contested territory and battleground.

There were some similarities that existed for both the North and the South when the Civil War began. Both sides believed they were fighting for a very just cause, which provided important motivation when the Civil War began. Southerners believed the North was threatening their entire way of life. Southerners believed they had the right to own slaves and were willing to defend that right. Northerners believed that saving the Union was vital. Many Northerners also were against slavery and believed that slavery needed to end. Another similarity was that both sides believed they would win the war. Northerners thought the war would be a quick one and would be a relatively easy victory. Southerners believed that the North would not have the desire to fight a long, drawn-out conflict, which would help the South achieve its goal of becoming independent.

There were differences that also existed. The South had better military leadership. Many of the military schools were located in the South, and some of the best generals lived in Southern states. For example, Robert E. Lee, who was considered the best general in the country, fought on the side of the South because Virginia, his home state, joined the Confederacy. The South also only had to fight a defensive war. The South did not have to capture the North's territory in order to achieve victory, which was not the case for the North.

The North had a decided advantage in several areas. There were more people living in the North, which contributed to a larger military force. The North had more industries than the South, as the South was mainly agricultural. As a result, the North had better weapons than the South. There were more miles of train tracks in the North, allowing for quicker and easier transportation of people and products. The North had more ships and a better navy, which aided the North in blockading the South's coast and transporting products by water. The North also had a great leader in President Lincoln, whose leadership skills were a huge asset for the North.

Popular opinion in the North and the South held that the war would be short and relatively bloodless. Northerners thought southerners would quickly capitulate when faced with overwhelming force, and southerners thought the North lacked the resolve to fight against southerners, who they thought were inherently better fighters. In both regions, calls for enlistment were (for about the only time in the conflict) answered enthusiastically. 

The major differences between the two regions were material. The vast majority of industry in the United States was in states that had not left the Union, and the Southern economy was based largely on cash crop agriculture, which they hoped to use to leverage European support for the Confederacy. The North also had a much larger population than the South, and it is important to remember that a very significant portion of the South's population of military-aged males were slaves, and the Confederacy refused to arm them. The North also had an enormous infrastructural advantage, with many more miles of railroad.