necessity vs demand

necessity and demand both are nouns.

Word	Noun	Adjective	Verb	Adverb
necessity	Yes	No	No	No
demand	Yes	No	Yes	No

As nouns, demand is a hypernym of necessity; that is, demand is a word with a broader meaning than necessity:

Other hypernyms of necessity include need.

necessity (noun)	demand (noun)
anything indispensable	the act of demanding
the condition of being essential or indispensable	required activity
	an urgent or peremptory request
	the ability and desire to purchase goods and services
	a condition requiring relief

necessity (verb)	demand (verb)
	request urgently and forcefully
	claim as due or just
	summon to court
	ask to be informed of
	lay legal claim to
	require as useful, just, or proper