government vs polity

government and polity both are nouns.

Word	Noun	Adjective	Verb	Adverb
government	Yes	No	No	No
polity	Yes	No	No	No

As nouns, polity is a hypernym of government; that is, polity is a word with a broader meaning than government:

government: the organization that is the governing authority of a political unit
polity: a politically organized unit

government (noun)	polity (noun)
the act of governing; exercising authority	shrewd or crafty management of public affairs
(government) the system or form by which a community or other political unit is governed	a politically organized unit
the study of government of states and other political units	the form of government of a social organization
the organization that is the governing authority of a political unit