demesne vs feoff

demesne and feoff both are nouns.

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

As nouns, feoff is a hyponym of demesne; that is, feoff is a word with a more specific, narrower meaning than demesne:

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

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