I'm a translator who works for a translation firm; despite not being a translator of historical documents (or all that familiar with history), sometimes we handle things such as period drama subtitles that include references to, among other things, the Chinese 王 (often with qualifiers [親王, 郡王, etc.], the significance of which seems to also vary.)
What little history I learned tell me that the word can refer to someone enfeoffed, or not; stipended greatly, or not; hereditary, or also not; their titles may refer to actual locations.....or also not.
(Google sometimes helps a lot, but also sometimes not.)
Usually, my clients and editors are happy enough with a "Prince of XX" (although a colleague once complained that Prince of Zhongxiao isn't a good rendition for 忠孝王 since that suggests Zhongxiao is a place); however, I've always wondered - just how exactly has this simple character been used differently in what are no doubt very different contexts throughout the states of China? Is there a "better" translation for, or a term in English that corresponds to, the term in general?
PS: I think I once read u/EnclavedMicrostate write a comment that somewhat covered the Ming system, but I also forgot where it was.
Before I begin, I would recommend that you check out the book by Hucker on Chinese imperial Official titles. The digital copy is available here.
The exact evolution of the 王 wang system throughout every dynasty is rather complicated, and I definitely do not have the knowledge to cover everything. So I hope to give you a quick overview and end off with some comments on translations.
In pre-imperial times, which is before the first huangdi (Qin Shi Huang), 王 was basically the title for a 'king'. This was actually the highest ruling title, which is why we would see it in names of 'Highest absolute' rulers (E.g. King Ping of Zhou ,周平王 zhou ping wang), or those who declare independence from the dynasty (E.g. King Wu of Chu ,楚武王 chu wu wang).
In the imperial times, as the highest title was changed to huangdi (皇帝), 王 evolved to be an aristocratic title just below the huangdi. This is also where different qualifiers would come in.
What little history I learned tell me that the word can refer to someone enfeoffed, or not; stipended greatly, or not; hereditary, or also not; their titles may refer to actual locations.....or also not.
For this, it really depends on the dynasty, or even the person. So it's best to look at it case-by-case.
親王 (qin wang) and 郡王 (jun wang) are the main 2 categories that will encompass most, if not all, 王 titles.
The difference between 親王 and 郡王 is their rank (and hence associated fief sizes, if any).
Quoting Hucker here:
親王, Imperial Prince, a designation conferred on all sons of each reigning Emperor other than the Heir Apparent. Imperial Princes were usually known by the names of territories with which they were (most often only nominally) enfeoffed
These are usually exclusive for nobilities, but in times of chaos exceptions do happen.
The territories enfeoffed would usually be rather huge, with a couple of commanderies. To address them, you address them by the name of the territory (which is usually one character). For example, 鲁王 (Lu wang) would be Prince of Lu.
Generally, certain location names are more 'prestigious' , usually corresponding to the stronger states' names during the Warring States/Spring & Autumn periods. For example, Qin (秦) and Chu (楚).
Quoting Hucker again:
郡王, Commandery Prince, high title of nobility , ordinarily prefixed with a place-name designating the noble's real or nominal fief
As the name suggests, these titles only grants fief of usually one, if not a few commanderies. They were normally granted to the sons of 親王s, but occasionally normal officials with great achievements can be granted these titles as well.
For the names of this type of prince, there are 2 broad categories: those with place names and those with descriptors.
It is also possible for names, be it 親王 or 郡王 , to have both the location name and the 'descriptors'.
To be more precise, the 'adjective' used are called Posthumous names (if the 'descriptors' were given after the said person died that is, if not they are just normal descriptors denoting positive connotations).
Because some titles are hereditary, there could be multiple princes with the same location name. To address those before the current prince, as well as to avoid confusion and differentiate between different princes , people would address previous princes together with their posthumous names.
Posthumous names are essentially honorary names given to worthy people (in this case, princes) as an summary of their life and accomplishments. In Chinese the whole construct is "[state][adjective][title]", which in English is typically translated as "[title][adjective] of [state]".
For example, there were more than 10 Prince of Qin (秦王,qin wang) in Ming Dynasty, and each have their own posthumous names. So if I were to address just one of them, it might be 秦惠王 (Qin hui wang, Prince Hui of Qin) or 秦宣王 (Qin xuan wang, Prince Xuan of Qin).
To end off, I would re-emphasize that a lot of things are really very case-by-case. Regarding differentiating locations from non-location names, I cannot offer you a comprehensive guide, but I can refer you to the China Historical GIS which has pretty comprehensive data on the historical location names in China.