Kentucky, Massachusetts, Pennsylvania, and Virginia call themselves commonwealths rather than states. Does this actually mean anything or is it just a name?
It’s just a name, not a legal description. Puerto Rico also calls itself a commonwealth.
Yes, but as Cecil makes clear, in the case of Puerto Rico there indeed is a legal difference. Puerto Rico is part of the US, but it’s not a state; its inhabitants are US citizens, but they don’t have any suffrage in US federal elections (OTOH, they don’t have to pay US federal taxes). Several attempts to turn Puerto Rico into a full state have been rejected in referenda by the island’s population.
This issue is currently being discussed on this thread: How many states?
In the case of Puerto Rico and the Northern Mariana Islands, the usage of “commonwealth” to refer to both their internal body politic AND to their particular flavor of Unincorporated Organized Territory of the USA is a matter of convenient political verbal gymnastics, based on that you have to call it something while satisfying (or avoiding the alienation of) multiple constituencies.
In the case of PR, they initially suggested “Free State”, “Associate State”, or Brit-style “Dominion”, but all along the 20th Century there were strong stateside objections to any term that could carry within it the implication that the US was commited to steward PR towards either independence OR statehood. So “Commonwealth” it was in English, while it was Associate Free State (Estado Libre Asociado) in Spanish, in order to satisfy local factions by pretending to give everyone a little of what they wanted. Then the UN threw all a curve ball, by coming up in the 1960s with the recognition of something called a “State in Free Association”, which is a form of “shared independence” and which is now used in the USA for the Marshall Islands, Palau and Micronesia. But we were not about to change the letterhead so Commonwealth/ELA it has stayed… (and the only real serious attempt to push for statehood was a 2-parter by the same administration, with 3-way and 4-way votes in 1993 and 1998, both times statehood could not break 46.5%; the only other vote, in 1967, was designed as a sort of “vote of confidence” by a pro-commonwealth admin)
Interestingly, there is no actual federal general definition of what is or is not included in a “commonwealth”: for PR and the NMI (and Guam’s repeatedly-ignored application) it’s custom-designed for each in the respective statutes. The apparent de-facto pattern for “commonwealths” as opposed to plain unincorporated territories is mainly that their internal organization is set forth in a constitution drafted by a local convention, rather than in a Congressional statute, and their capacity to levy taxes and incur debt is independent of Congress.
As to KY, VA, MA, PA, “commonwealth” is the name assumed in their constitutions for their orgainzed body politic, i.e. for their “state”; however, their relationship to the Federal government and to the other 46 components of the USA is that of a “State” of the Union. Technically, any of the 50 could style itself a state or commonwealth or landstead or political holding corporation or jelly donut or just plain use its geographic name with no descriptor attached as its legal title, as long as they remain organized according to the republican form of government.