crucial vs essential

crucial is not a noun while essential is a noun.

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

As adjectives, crucial and essential are synonyms defined as:

Other synonyms of crucial include all-important, all important, of the essence.

crucial (noun)	essential (noun)
	anything indispensable

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