Plato is normative and he uses deductive reasoning whereas Aristotle uses deductive as well as inductive logic. Aristotle used the imperial method when he studied 158 constitutions of his time. Aristotle theory of evaluation is also based on empirical investigation.
Aristotle uses a method of biology where he classifies the constitution thus, from Aristotle the tradition of scientific study of politics began. This is the reason professor Maxey calls Plato as the father of political philosophy and Aristotle as the father of political science.
Plato’s book republic is not a book on politics primarily it is a book on ethics. Aristotle’s book titled political is primarily dealing with the subject of politics.
As a father of political science Aristotle has given birth to the number of ideologies/ideological perspectives- convictism, Liberalism, communalism, etc.
It was Aristotle who treated political science as the master science he rightfully deserves as known as the father of political science. He was the first person to establish that the nature of men is political.