It would be more like the empire is the Yankee Union & the Stormcloaks are the Rebel Confederates. This anology would make more logical coherence in the world of Skyrim Players.
That would only be a fit anology if:
- the Yankees would just have been beaten by a foreign government of religious and racial fanatics and were now a spent force
- The Yankees were currently obliged to carry out the totalitarian policies of the invaders on their own soil
- The Rebels would not support slavery and their rebellion would consequently be unrelated to that issue
The best anology (no anology is perfect) is still WW2 with the Empire as the Vichy Governement. This makes Ufric not a Hitler, but an anti-Hitler