This isn't about good versus evil, especially not in an RPG sense - the world of Game of Thrones doesn't care one whit for good vs. evil, it's central conflict is better described as Hot (Lord of Light, Dragons) vs. Cold (Night King, Undead). The differences are actually a matter of Dany's understanding of how wars are fought versus Jon's understanding of the same and the impacts that has across their respective cultural backdrops.
Dany has learned the ways of warfare in Essos, a context similar to Central Asia where everyone rules absolute tyrannies, might explicitly makes right, and
not inflicting horrible tortures on your enemies is more likely to be problematic than otherwise. In the show, specifically, she finally won in Mereen not by making compromises and placating the defeated but by unleashing the dragons and enacting some choice burnings. The Essos environment is the kind of place that
Timur would feel right at home in, it doesn't have a feudalistic concept of limited war.
Westeros, by contrast, has just such a concept of limited war, in fact it has an extremely highly developed one with, in addition to all the normal feudal traditions of land redistribution, title-stripping, inheritance alteration and the rest, also has the mechanism of exiling criminals to the Night's Watch. Case in point, the entire War of the Five Kings was, if not started outright, greatly exacerbated by Joffery's insane decision to kill Ned Stark and not let him take the black as had been promised. Jon, like Ned and Rob before him, believes extremely strongly in this system of feudal justice and that's why he spared the Karstark and Umber heirs even when Sansa - who's been schooled in the Littlefinger way of realpolitck - counseled him not to.
Importantly, that feudal compact has largely collapsed through much of Westeros, to the point the even Randyll Tarly broke the bonds that tied him to House Martell and chose to fight for the Lannisters instead (a somewhat dubious point in the first place given his supposed character traits), but it remains true
in the North, and both Jon and Dany are having problems with it. Jon because he believes, quite correctly, that the old system is almost certainly unlikely to survive the giant battle with ice zombies to come and so debating who rules Winterfell when it's probably only got a ten percent of even existing next year is really dumb. Dany because she just believes her obvious might means the northerners shouldn't be so much as thinking they'll disobey her, while underestimating their nearly suicidal obstinacy. This is unfortunately compounded, in the show, by a failure to properly show the size disparity between the forces at play.