essential vs crucial

essential is a noun but crucial is not a noun.

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

As adjectives, essential and crucial are synonyms defined as:

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

essential (noun)	crucial (noun)
anything indispensable

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