Explain Like I'm Five

Though honestly the nuance of all this could be argued forever. My broad point is that if you look at an empire vs a nation state, each with autocratic control. The nation states are much more likely to require conformity from their population not just wealth.

I think I'd agree with that, even if empires have a great deal of variance. The only nation states that are tolerant I can think of are very modern indeed, and there seems to be a trend back to enforcing homogeneity. For the sake of completeness we should probably mention small-scale feudal (agricultural) or band (hunter-gatherer) systems which are neither. Feudal systems can be anywhere in that range, I think, and often adapt very fast if participation with outsiders becomes important, which is basically how empires grow. Band societies are atomic by definition and will have no overall regional policy.

I guess a good example of the top of my head would be the the Great Hedge of India.

I know that they didn't try to completely reorganise India, which is good. Obviously, in Canada colonization didn't go well for the natives. At times it was straight up genocidal, and probably wouldn't have even been as subtle as it was if now-independent America hadn't done most of the work already. In South Africa it was kind of a weird situation because there was another legacy group of Europeans in the picture, and I know less about the rest of British Africa.

I've heard the idea that the British were nicer before IRL, but it mostly seems like an echo of old propaganda when I do. I'd take them over the earlier Spanish or Portuguese any day, but they seem pretty comparable with the French, and behind someone like the Romans who were truly apathetic towards the customs of their colonies in most cases, and even allowed colonial subjects to ascend to citizenship as a regular course of events. I don't know, maybe that wasn't your point but I felt the need to bring it up.