fief vs acres

fief and acres both are nouns.

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

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

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

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

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