The difference between Essential and Unneeded

When used as adjectives, essential means necessary, whereas unneeded means not needed.

Essential is also noun with the meaning: a necessary ingredient.

check bellow for the other definitions of Essential and Unneeded

Essential as an adjective:

Necessary.
Essential as an adjective:

Very important; of high importance.
Essential as an adjective (biology):

for survival but not by the organism, thus needing to be ingested
Essential as an adjective:

Being in the basic form; showing its essence.

Examples:

"Don’t mind him being grumpy. That’s the essential Fred."
Essential as an adjective:

Really existing; existent.
Essential as an adjective (of a [[lamination]] of a 3-[[manifold]]):

Such that each complementary region is irreducible, the boundary of each complementary region is incompressible by disks and monogons in the complementary region, and no leaf is a sphere or a torus bounding a solid torus in the manifold.

Examples:

"rfex difference between 1 and 2"
Essential as an adjective (medicine):

Idiopathic.