friend vs endorser

friend and endorser both are nouns.

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

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

friend (noun)	endorser (noun)
a person you know well and regard with affection and trust	someone who expresses strong approval
a person with whom you are acquainted	a person who transfers his ownership interest in something by signing a check or negotiable security
an associate who provides cooperation or assistance
a person who backs a politician or a team etc.