I always found the social class system to be very fascinating. People who know me know that I am kind of a "royal" buff and I have noticed that many seem to get confused about the difference between "royal" and "noble" titles. I thought it would be interesting to include a little information on this subject for informational purposes more than anything. I actually tried to keep this classification system as fairly accurate as compared to the real world as I could with perhaps a few modifications. Remember, however, that your DM can adapt this system in a way to fit your campaign world if you are not using Hyerune. You may not even want to include all the various titles of nobility.
There are a couple key points you should keep in mind. The terms "royal" and "noble" are actually two completely different ranks and are not the same thing. Someone who is described as "royal" comes from the ruling dynasty, or family, of a specific country. They would be somehow related to the king or queen or the ruling sovereign. The Royal Family usually includes the King and Queen, their children and grandchildren and sometimes even the brothers and sisters of the monarch. Someone who is purely "noble" means that person is an aristocrat but not necessarily related to the ruling family. Often, these persons are weathly landowners or war heroes who inherited their titles or were granted a "peerage," or noble title, from the monarch. In some countries, a noble may actually have more power, wealth, land or prestige than a royal person. A person of royal rank will generally outrank a person of noble rank, however, regardless of their title.
Below is a brief classification system of the social rankings and noble titles of Hyerune starting with the highest ranking title first. Titles on the same line are of equal rank.
Emperor / Caliph / Padishah / Maharaja / Khakhan
King / Sultan / Raja / Shah
Archduke
Grand Duke
Grand Prince
Duke / Herzog / Pasha / Bey / Prelate / Archcleric / Archmage
Prince / Emir / Khan
Margrave / Marquess / Landgraf / March Lord
Count / Earl / Graf / Jarl / Bishop
Viscount / Archbaron
Baron
Baronet / Abbott / High Ranking Military officers
Knight / Paladin / Ranger Lord / Low Ranking Military officers
Esquire / Prior / Freeholder / Minor Clergy
Heads of Small Communities
Gentlemen / Landholders
Merchants
Craftsmen
Tradesmen
Freemen
Professional Soldiers
Village Elders
Mercenaries
Laborers
Apprentices
Serfs / Servants
Peasants / Beggers
Slaves