friend vs chum

friend and chum both are nouns.

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

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

friend (noun)	chum (noun)
a person you know well and regard with affection and trust	a large Pacific salmon with small spots on its back; an important food fish
a person with whom you are acquainted	bait consisting of chopped fish and fish oils that are dumped overboard to attract fish
an associate who provides cooperation or assistance	a close friend who accompanies his buddies in their activities
a person who backs a politician or a team etc.