requirement vs need

requirement and need both are nouns.

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

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

Other hyponyms of requirement include desideratum, must, want.

requirement (noun)	need (noun)
something that is required in advance	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
required activity	anything that is necessary but lacking
anything indispensable	a condition requiring relief
	a state of extreme poverty or destitution

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