primary vs essential

primary and essential both are nouns.

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

primary (noun)	essential (noun)
a preliminary election where delegates or nominees are chosen	anything indispensable
one of the main flight feathers projecting along the outer edge of a bird's wing
coil forming the part of an electrical circuit such that changing current in it induces a current in a neighboring circuit
(astronomy) a celestial body (especially a star) relative to other objects in orbit around it

primary (adjective)	essential (adjective)
of first rank or importance or value; direct and immediate rather than secondary	basic and fundamental
of or being the essential or basic part	defining rights and duties as opposed to giving the rules by which rights and duties are established
most important element	being or relating to or containing the essence of a plant etc
not derived from or reducible to something else; basic	of the greatest importance
	absolutely necessary; vitally necessary