demand vs deficiency

demand and deficiency both are nouns.

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

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

Other hyponyms of demand include lack, want, necessity.

demand (noun)	deficiency (noun)
the act of demanding	lack of an adequate quantity or number
required activity	the state of needing something that is absent or unavailable
an urgent or peremptory request
the ability and desire to purchase goods and services
a condition requiring relief

demand (verb)	deficiency (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