fief vs demesne

fief and demesne both are nouns.

Word	Noun	Adjective	Verb	Adverb
fief	Yes	No	No	No
demesne	Yes	No	No	No

As nouns, demesne is a hypernym of fief; that is, demesne is a word with a broader meaning than fief:

fief: a piece of land held under the feudal system
demesne: extensive landed property (especially in the country) retained by the owner for his own use

Other hypernyms of fief include acres, estate, land, landed estate.

fief (noun)	demesne (noun)
a piece of land held under the feudal system	territory over which rule or control is exercised
	extensive landed property (especially in the country) retained by the owner for his own use