Technical military and industrial comparisons aside, the Union had the inside lines for personnel, and that was a substantial advantage. Character matters; the best chance for the Confederate States would have been in a weak President of the United States who found appeasement or compromise better choices than war. Lincoln wasn’t so disposed to let the will of slave oligarchs prevail over federal laws and state’s rights.
States right’s to not comply with the Fugitive Slave Act of 1850 was an issue that Wisconsin and Vermont tried to enact through state high court decisions that the U.S. Supreme Court overturned. Southern slave-owners felt they had a right to recapture escaped slaves anywhere in the United States. That law was effectively reversed in the eventful year of 1861, with passage of The Confiscation Act barring recapturing of escaped slaves. Fugitive Slave Act of 1850 - Wikipedia
West Point was a federal education and training facility. The officers and graduates had of course to choose what side they would fight on. The Northern forces commanded the loyalists and best of the lot. The South got the decorous commandant of that young men’s school; an Army engineer named Robert E. Lee. The north knew the military ability of southern commanders. Lee and Grant each fought in the Mexican war. Lee was attached as an aide to Gen Scott. Grant personally fought in a battle against Mexicans. Later he set artillery to fire from a second story of a building in the attack on Mexico City with positive results.
Lee had married the daughter of George Washington’s (adopted) son. His father had been convicted of being a land swindler, and Lee saw the Army as a way to safely promote himself without gambling . He cut a good figure on a horse, and couldn’t resist the promotion to Supreme Commander of Confederate Forces. The Confederate leadership was flawed. Lincoln alternatively was able to experiment with his military leaders until finding the best.
Historians have written that Lee couldn’t control his boisterous, argumentative Generals. Lee wasn’t the kind of brawling tough guy to put down enmity and coordinate planning among his subordinates. Neither was he able to follow orders well enough. Confederate President Jefferson Davis ordered Lee not to go north of the Potomac River again. Lee disobeyed and the expedition to Maryland and beyond began with results that seriously weakened southern strength. Like perennial presidential candidates, Lee may not have been able to resist the prospect of capturing Washington D.C. for-himself.
The northern forces had better leadership and personnel than the south. They also had God on their side, insofar as egalitarianism- God is no respecter of persons, required that no human slavery exist, that oligarchy, plutonomy or royalty not occlude democracy. The Confederacy was doomed because it was evil.