government vs political science

government and political science both are nouns.

Word	Noun	Adjective	Verb	Adverb
government	Yes	No	No	No
political science	Yes	No	No	No

As nouns, government and political science are synonyms defined as:

government and political science: the study of government of states and other political units

Other synonyms of government include politics.

government (noun)	political science (noun)
the act of governing; exercising authority	the study of government of states and other political units
(government) the system or form by which a community or other political unit is governed
the study of government of states and other political units
the organization that is the governing authority of a political unit