demesne vs principality

demesne and principality both are nouns.

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

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

demesne (noun)	principality (noun)
territory over which rule or control is exercised	territory ruled by a prince
extensive landed property (especially in the country) retained by the owner for his own use