party favour vs keepsake

party favour and keepsake both are nouns.

Word	Noun	Adjective	Verb	Adverb
party favour	Yes	No	No	No
keepsake	Yes	No	No	No

As nouns, keepsake is a hypernym of party favour; that is, keepsake is a word with a broader meaning than party favour:

party favour: souvenir consisting of a small gift given to a guest at a party
keepsake: something of sentimental value

Other hypernyms of party favour include relic, souvenir, token.

party favour (noun)	keepsake (noun)
souvenir consisting of a small gift given to a guest at a party	something of sentimental value