knighthood vs nobility

knighthood and nobility both are nouns.

Word	Noun	Adjective	Verb	Adverb
knighthood	Yes	No	No	No
nobility	Yes	No	No	No

As nouns, nobility is a hypernym of knighthood; that is, nobility is a word with a broader meaning than knighthood:

Other hypernyms of knighthood include aristocracy.

knighthood (noun)	nobility (noun)
aristocrats holding the rank of knight	the quality of elevation of mind and exaltation of character or ideals or conduct
	a privileged class holding hereditary titles
	the state of being of noble birth