demand vs necessity

demand and necessity both are nouns.

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

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

Other hyponyms of demand include deficiency, lack, want.

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

demand (verb)	necessity (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