The difference didn't seem to start a war when Jackson was President.
Only when the "rights" of the southern slave powers were threatened by the legal victory of a President belonging to a party that wanted to limit slavery to its current extent, as had the Northwest Ordinance, only then was it a cause for war.
The Slavers sought to continue their position, gained by oppression of both blacks (in the obvious way) and whites ( by drafting them into the militia, used for slave patrols), and open western lands for their expansion. Southern agricultural practices were not efficient, intending to get the maximum out of land in a few years, followed by selling out, dissolving the slave property, and starting again further west.
The Southern fire eaters had overinvested (speculated) in slave property, and closing territories to their property would have depressed the value of their investment.
That, dear gentlemen, is the reason for the war. They demanded that the Union be run to their advantage, or they would quit, and drag out as much as they could get away with out of spite. It cost about 900,000 lives to resolve their issue. They lost.
So did the poor whites drafted two and three times over into the southern slave patrol-militia, then into the "Confederate" army, then, after being wounded and sent home to recover, they were again often drafted into state militias. Meanwhile the wealthy slavers arranged that they didn't have to go if they owned a certain number of slaves.
Sure, there were injustices in the north too. No doubt. I don't buy the Lost Cause stuff, mostly invented (and i have read primary sources on that) after the war to justify their rebellion.
didn't seem to start a
Slavery was THE issue?
"I have no purpose, directly or indirectly, to interfere with the institution of slavery in the states where it exists. I believe I have no lawful right to do so."
From Lincoln's first inaugural address
"My paramount object in this struggle is to save the Union, and it is not either to save or destroy slavery."
Lincoln in a 1862 letter to Horace Greeley, New York Daily Tribune editor
A precursor for a War Between the States came in 1832, when South Carolina called a convention to nullify tariff acts of 1828 and 1832, referred to as the "Tariffs of Abominations." A compromise lowering the tariff was reached, averting secession and possibly war. The North favored protective tariffs for their manufacturing industry. The South, which exported agricultural products to and imported manufactured goods from Europe, favored free trade and was hurt by the tariffs. Plus, a northern-dominated Congress enacted laws similar to Britain's Navigation Acts to protect northern shipping interests.
Shortly after Lincoln's election, Congress passed the highly protectionist Morrill tariffs.
That's when the South seceded, setting up a new government. Their constitution was nearly identical to the US. Constitution except that it outlawed protectionist tariffs, business handouts and mandated a two-thirds majority vote for all spending measures.
BTW, 620,000 is the accepted number for WBTS killed, not 900,000.