The difference is the USA won their independence and the CSA lost and got consigned to the circular filing cabinet of history.
Err you might as well say the difference between the US and the Nazi's in WW2 was that the US won.
The CSA was a fundamentally evil state that whose entire reason for existing was fear that
A) Thanks to population growth in the "Free States" the South no longer dominated Congress and the POTUS elections thanks to it's slaves.
B) They were afraid that the election of the Republicans meant they would no longer be able to spread slavery to all the territories (and ideally all of he "Free States" as well) and preserve the institution of chattel slavery forever. Not even fear Lincoln would outright abolish slavery. Just fear that the Republicans wouldn't let them spread slavery everywhere and potentially conquer large parts of Latin America to spread slavery there too.
The US did terrible things during the war and terrible things before and after. But it's entire reason for existence wasn't preserving and slavery as far as possible forever. The same way Nazi Germany was fundamentally founded to allow Germany to conquer vast swathes of Europe and genocide 99 percent of the populace (at least at a point in history where that was now regarded as being evil in every way)
If the CSA had won a substantial portion of the members of this board might instead be slaves even to this day. In the same way that if Nazi Germany won a substantial portion of the membership of this board would be dead or never born because their parents/grandparents were starved/shot/gassed/beaten to death or otherwise horribly murdered.
And to add to that if the CSA hadn't seceded the South would when combined with northern Doughfaces have been able to preserve slavery for an unknown amount of time and even spread it to some territories as a compromise. They would have been able to prevent the Lincoln Administration from doing much.
The US has done some fucked up things but it was