pact vs treaty

pact and treaty both are nouns.

Word	Noun	Adjective	Verb	Adverb
pact	Yes	No	No	No
treaty	Yes	No	No	No

As nouns, pact and treaty are synonyms defined as:

Other synonyms of pact include accord.

pact (noun)	treaty (noun)
a written agreement between two states or sovereigns	a written agreement between two states or sovereigns