government vs authorities

government and authorities both are nouns.

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

As nouns, government and authorities are synonyms defined as:

government and authorities: the organization that is the governing authority of a political unit

Other synonyms of government include regime.

government (noun)	authorities (noun)
the act of governing; exercising authority	the organization that is the governing authority of a political unit
(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