realty vs demesne

realty and demesne both are nouns.

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

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

realty: property consisting of houses and land
demesne: extensive landed property (especially in the country) retained by the owner for his own use

Other hyponyms of realty include acres, estate, land, landed estate, land, dead hand, mortmain.

realty (noun)	demesne (noun)
property consisting of houses and land	territory over which rule or control is exercised
	extensive landed property (especially in the country) retained by the owner for his own use