souvenir vs favor

souvenir and favor both are nouns.

Word	Noun	Adjective	Verb	Adverb
souvenir	Yes	No	No	No
favor	Yes	No	Yes	No

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

Other hyponyms of souvenir include love-token, favour, party favor, party favour.

souvenir (noun)	favor (noun)
something of sentimental value	an act of gracious kindness
a reminder of past events	souvenir consisting of a small gift given to a guest at a party
	an advantage to the benefit of someone or something
	an inclination to approve
	a feeling of favorable regard