kingdom vs demesne

kingdom and demesne both are nouns.

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

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

Other hypernyms of kingdom include domain, land.

kingdom (noun)	demesne (noun)
a basic group of natural objects	territory over which rule or control is exercised
a monarchy with a king or queen as head of state	extensive landed property (especially in the country) retained by the owner for his own use
the highest taxonomic group into which organisms are grouped; one of five biological categories: Monera or Protoctista or Plantae or Fungi or Animalia
the domain ruled by a king or queen
a country with a king as head of state
a domain in which something is dominant