necessary vs essential

necessary and essential both are nouns.

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

As nouns, necessary and essential are synonyms defined as:

Other synonyms of necessary include necessity, requirement, requisite.

necessary (noun)	essential (noun)
anything indispensable	anything indispensable

necessary (adjective)	essential (adjective)
absolutely essential	basic and fundamental
unavoidably determined by prior circumstances	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