postulate vs govern

postulate is a noun but govern is not a noun.

Word	Noun	Adjective	Verb	Adverb
postulate	Yes	No	Yes	No
govern	No	No	Yes	No

As verbs, govern is a hyponym of postulate; that is, govern is a word with a more specific, narrower meaning than postulate:

Other hyponyms of postulate include claim, exact, take, draw, cost, cry for, cry out for, compel.

postulate (noun)	govern (noun)
(logic) a proposition that is accepted as true in order to provide a basis for logical reasoning

postulate (verb)	govern (verb)
take as a given; assume as a postulate or axiom	exercise authority over; as of nations
maintain or assert	direct or strongly influence the behavior of
require as useful, just, or proper	bring into conformity with rules or principles or usage; impose regulations
	require to be in a certain grammatical case, voice, or mood