they act in a different way from the other, which they very much do. The basis of their power comes from different roots, and because of that, they have different interests, different goals, different avenues of action, different preferences in compromise with wider society.

I firmly disagree. There is no meaningful difference in motivation or expected outcome. The behaviour is functionally identical. In neither case is there any commitment to compromise with society, both Aristocracy and Plutocracy leverage economic factors to control and contain the wider community, to arbitrary and capricious ends; frequently little more than the further consolidation of power. The terminology is different, it sounds different, but it does not behave different in any meaningful way. Any social contract is entirely grounded in what we choose to demand as a society, not intrinsic to the flavour of elite class.

It’s the same motive, the same tools, and the same outcome, just re-branded and with a fresh coat of paint. Plutocracy in this era leverages scientific and evidence based psychological conditioning, social control, and new communication mediums to play on a variety of fundamental cognitive biases and limitations instead of leveraging religion alone as the primary means of containment of the governed, nothing more. As I said, it’s Aristocracy with a business degree. If you want to get specific it’s Aristocracy with a business degree and a marketing team instead of just the clergy.

The point is that the basis of aristocratic power comes (in part) from a position of extraordinary legal privilege, not simply being able to escape consequences for crimes.

We’re so very close but we’re not quite getting that last point. What I’m saying is it’s a distinction with very little meaningful difference. It’s interesting from an academic point of view, but that’s it. How they rationalize their privilege and sell their legitimacy to people makes no difference.

In principle you are correct, in practice the functional difference is very much negligible. As anyone who has ever tried to hold a plutocrat accountable in court can tell you, their equality under the law is more theoretical than how the world really works. The cults of personality, the careful reputational management, the nepotism and cronyism, dynastic rule and insularity, it’s all there, it’s just got a different window dressing.

On paper their power is different. In practice, not so much.

Fascism is what you get when Aristocracy gets a business degree. The difference between a feudal lord and a CEO is non-farm income.