voucher vs friend

voucher and friend both are nouns.

Word	Noun	Adjective	Verb	Adverb
voucher	Yes	No	No	No
friend	Yes	No	No	No

As nouns, friend is a hypernym of voucher; that is, friend is a word with a broader meaning than voucher:

voucher: someone who vouches for another or for the correctness of a statement
friend: a person who backs a politician or a team etc.

Other hypernyms of voucher include admirer, booster, champion, protagonist, supporter.

voucher (noun)	friend (noun)
a negotiable certificate that can be detached and redeemed as needed	a person you know well and regard with affection and trust
a document that serves as evidence of some expenditure	a person with whom you are acquainted
someone who vouches for another or for the correctness of a statement	an associate who provides cooperation or assistance
	a person who backs a politician or a team etc.