No law, but arbitrary force supports the despot. That is the evolving Obama. It is no minor distinction.
FWIW, my points are from a guy to whom the Framers paid a lot of attention, Montesquieu.
All hereditary lines had a beginning, no law but force enabled them. In that way, there is no difference. There is no legitimate line of kings in the western world. That people accepted the divine right of kings to rule over them speaks to a desire for security over freedom. As for Montesquieu, as a Frenchman he should know better considering the history of the monarchy and force in France.