The point is how they were using the terms at the time of the founding of the country.
But only one of the terms was carried forward into the Constitution.
Supreme Court Justice Horace Gray in writing the majority opinion in U.S. v. Wong Kim Ark (1898):
“Subject’ and ‘citizen’ are, in a degree, convertible terms as applied to natives; and though the term ‘citizen’ seems to be appropriate to republican freemen, yet we are, equally with the inhabitants of all other countries, ’subjects,’ for we are equally bound by allegiance and subjection to the government and law of the land.”