At the time that those involved in the construction of and the execution of our Declaration of independence, each one of these future signees were subjects to the crown of England, and therefore were not citizens, of the British crown, but rather its subjects. A careful reading though of the Declaration of independence demonstrates that the final Authorized and signed Version as written by Thomas Jefferson uses the word people ten times to refer to the peoples that made up the "thirteen united states of America" and once was used the word, citizens, when referring to the present King of Great Britain, with: "He has constrained our fellow Citizens taken Captive on the high Seas." These words of "people" as well as "citizens" are words that we as a people, and we as citizens of this great nation, take for granted at the present time, but at the time of the Declaration of Independence, these words were, in fact, revolutionary.
The fact of the matter is that this momentous shift in thinking, as to what type of people that we were to become, did not even come immediately to the incomparable Thomas Jefferson, for as reported by the washingtonpost.com, in an earlier Declaration of Independence draft Thomas Jefferson as discovered by research chemist Dr. Fanella France reported that: "It's quite amazing how he morphed 'subjects' into 'citizens'". Not only is this decisive change from subjects to citizens, from subjects to a people, the critical part of the very foundation of what became the greatest republic in the annals of all history, but it also set the stage so that our governing document, our present Constitution, was not a document, that created yet another king, and thereby a monarchy, but a President and a republic, with three separate and distinct branches of governance, rather than the European model of monarchies which our independence broke us free from.
To be a subject is to be under the thumb and domain of a power that is sovereign unto itself and thereby has the power to dictate to its subjects what they can or cannot do, in conjunction with parliamentary protocol along with the inevitable political give and take. On the other hand, a government of the people, by the people, and for the people is a nation of citizens that have a voice, and with that voice they can freely assemble, so too they can petition their representatives and their government, they have enumerated rights, a government of both checks and balances, and a government that is responsive to and must answer to its citizenry.
There can never be equality under the law, in a country to which you are a subject, but equality under the law is a fundamental tenet of citizens in a free country to which all are entitled to take part in the beneficence of its collective wealth and productivity. America is great because it has responsive citizens, and each of those citizens are gifted with the same inalienable rights, and not one of these citizens will ever be compelled to bow or genuflect to any domestic earthly king.