a major difference between monarchial power and a republic is
Republic A republic (Latin: res publica) is a form of government in which the country is considered a "public matter", not the private concern or property of the rulers. The primary positions of power within a republic are not inherited. It is a form of government under which the head of state is not a monarch.[1][2][3]
Monarchy of the United Kingdom The monarch and his or her immediate family undertake various official, ceremonial, diplomatic and representational duties. As the monarchy is constitutional, the monarch is limited to non-partisan functions such as bestowing honours and appointing the Prime Minister. The monarch is, by tradition, commander-in-chief of the British Armed Forces. Though the ultimate formal executive authority over the government of the United Kingdom is still by and through the monarch's royal prerogative, these powers may only be used according to laws enacted in Parliament and, in practice, within the constraints of convention and precedent.