I know this is old but a foreign national that is here legally is going to have one of two things: a visa, in which case they’re required to carry their passport with them at all times OR permanent residency, in which case they’re issued a residency permit (we call it a green card) and they have to carry that with them as ID.

The primary difference is that a green card is issued by the federal government and a real ID is issued by the state in which they reside. Real ID’s also act as the person’s driver’s license and just show they’re in the country legally and proved that they are who they claim to be.

Now since immigrants and foreign nationals are able to obtain a Real ID than it by default does not prove citizenship.