Son of heaven: the highest rank of the nobility, the "king of the world", the land and people in the world belong to him and are maintained by the contributions of various vassal States.
Warlords: With fiefs, they can establish a country with diplomatic, campaign, taxation and alliance rights. And help the emperor rule the world (flat world). The land and people of a country are all his.
Doctor: It's a subordinate of the vassal, who helps the vassal to govern the country. He has the right to fief and tax, but the person who fief is not his.
Family: No site, no financial power and no connections, helping doctors manage affairs (Qijia)
Literati: No fief, no financial power or people, only responsible for reading, Xiu De, (cultivate one's morality).
The more special nobility is the gentry, whose original meaning is a person who studies and cultivates himself, and its extended meaning is a kind of noble who is more special but not humble, such as samurai, bachelor, scholar and so on. They don't farm, do business or work. We should know that anyone who occupies the highest position in objective cognition will become the ruling class, which is also the fundamental reason why the gentry can finally replace the son of heaven, princes, doctors and aristocratic families to become the ruling class.