duke vs peer

duke and peer both are nouns.

Word	Noun	Adjective	Verb	Adverb
duke	Yes	No	No	No
peer	Yes	No	Yes	No

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

duke: a British peer of the highest rank
peer: a nobleman (duke or marquis or earl or viscount or baron) who is a member of the British peerage

duke (noun)	peer (noun)
a British peer of the highest rank	a person who is of equal standing with another in a group
a nobleman (in various countries) of high rank	a nobleman (duke or marquis or earl or viscount or baron) who is a member of the British peerage

duke (verb)	peer (verb)
	look searchingly