friend vs campmate

friend and campmate both are nouns.

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

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

friend (noun)	campmate (noun)
a person you know well and regard with affection and trust	someone who lives in the same camp you do
a person with whom you are acquainted
an associate who provides cooperation or assistance
a person who backs a politician or a team etc.