Why did the North and South disagree about slavery?

the north wanted to block slavery while the south sorta encouraged it

Explanation:

The North and South disagreed about slavery due to the ideals that slavery was an advantage to the civil war effort. Nevertheless, cotton and other cash crops were highly influential in the markets of the South when the union wanted to control all labor intensive works for taxation

Explanation:

people can eat food during that time

which time period is this? or is this story fictional, i'm going to need more info to answer this question