backup man vs peer

backup man and peer both are nouns.

Word	Noun	Adjective	Verb	Adverb
backup man	Yes	No	No	No
peer	Yes	No	Yes	No

As nouns, peer is a hypernym of backup man; that is, peer is a word with a broader meaning than backup man:

backup man: someone who takes the place of another (as when things get dangerous or difficult)
peer: a person who is of equal standing with another in a group

Other hypernyms of backup man include compeer, equal, match.

backup man (noun)	peer (noun)
someone who takes the place of another (as when things get dangerous or difficult)	a person who is of equal standing with another in a group
	a nobleman (duke or marquis or earl or viscount or baron) who is a member of the British peerage

backup man (verb)	peer (verb)
	look searchingly