I know there are 4 Commonwealths (PA, VA, MA, and MD(?) ) So what’s the difference? I remember an episode of Cops where the officer explained to a motorist after citing him that he would have to go to court to answer to the Commonwealth. Whereas I would have to go to state court.
Is there a huge difference, or just semantics?
It’s just a title or “styling” of the official name of the state (or territory). If you look at the seal of the “State” of Connecticut you’ll see that it gives its name in Latin as “Republic” of Connecticut.
There are some theories about the usage e.g. that there are no unincorporated jurisdictions, etc., but in reality it is absolutely up to each state to title itself “state of” or “commonwealth of”, or “united counties of”, or “jelly doughnut of”. In the case of PA, VA and MA there is the likelihood that they adopted it to rhetorically emphasize that the body politic of They the People of Each, antecedes their condition as a “state” (KY probably just carried it over from when it was a part of Virginia) .
In the case of the overseas territories, “Commonwealth” is used to refer to those that are organized internally according to a Constitution drafted by a local Constitutional Convention and then approved by Congress, rather than by one entirely crafted in DC – Puerto Rico (in which case it’s an entirely different word than the term used in Spanish to title the entity) and the Northern Mariana Islands. But still, the point is there is no single, uniform, written-down-statutory definition of what is or is not a “commonwealth” – it’s up to whatever gets approved when the enabling bill is passed.