need vs deficiency

need and deficiency both are nouns.

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

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

Other hyponyms of need include lack, want, necessity.

need (noun)	deficiency (noun)
the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior	lack of an adequate quantity or number
anything that is necessary but lacking	the state of needing something that is absent or unavailable
a condition requiring relief
a state of extreme poverty or destitution

need (verb)	deficiency (verb)
have need of
have or feel a need for
require as useful, just, or proper