souvenir vs reminder

souvenir and reminder both are nouns.

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

As nouns, reminder is a hypernym of souvenir; that is, reminder is a word with a broader meaning than souvenir:

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