convention vs pact

convention and pact both are nouns.

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

As nouns, pact is a hypernym of convention; that is, pact is a word with a broader meaning than convention:

Other hypernyms of convention include accord, treaty.

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