requirement vs essential

requirement and essential both are nouns.

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

As nouns, requirement and essential are synonyms defined as:

Other synonyms of requirement include necessary, necessity, requisite.

requirement (noun)	essential (noun)
something that is required in advance	anything indispensable
required activity
anything indispensable

requirement (adjective)	essential (adjective)
	basic and fundamental
	defining rights and duties as opposed to giving the rules by which rights and duties are established
	being or relating to or containing the essence of a plant etc
	of the greatest importance
	absolutely necessary; vitally necessary