I suspect you are referring to the presidents of the Congress of Confederation under the Articles of Confederation, the system of government that ruled the United States from 1781 (ratification by the states) to 1789 (ratification of the Constitution of the United States, which replaced it). The President of Congress was mostly an administrative functionary rather than a chief executive - he ensured the proper working of the body, but held little power in excess of that of any other Congressman. There is no correlation between this role and that of President under the Constitution.