eternal vs everlasting

eternal is not a noun while everlasting is a noun.

Word	Noun	Adjective	Verb	Adverb
eternal	No	Yes	No	No
everlasting	Yes	Yes	No	No

As adjectives, eternal and everlasting are synonyms defined as:

Other synonyms of eternal include aeonian, ageless, eonian, perpetual, unceasing, unending.

eternal (noun)	everlasting (noun)
	any of various plants of various genera of the family Compositae having flowers that can be dried without loss of form or color

eternal (adjective)	everlasting (adjective)
tiresomely long; seemingly without end	continuing forever or indefinitely
continuing forever or indefinitely	without qualification; used informally as (often pejorative) intensifiers