pact vs convention

pact and convention both are nouns.

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

As nouns, convention is a hyponym of pact; that is, convention is a word with a more specific, narrower meaning than pact:

Other hyponyms of pact include alliance, commercial treaty, pacification, peace, peace treaty.

pact (noun)	convention (noun)
a written agreement between two states or sovereigns	the act of convening
	orthodoxy as a consequence of being conventional
	something regarded as a normative example
	(diplomacy) an international agreement
	a large formal assembly