reminder vs souvenir

reminder and souvenir both are nouns.

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

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

Other hyponyms of reminder include deja vu, memento, memento mori, shades.

reminder (noun)	souvenir (noun)
an experience that causes you to remember something	something of sentimental value
a message that helps you remember something	a reminder of past events
someone who gives a warning so that a mistake can be avoided