eternal vs aeonian

eternal and aeonian both are adjectives.

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

As adjectives, eternal and aeonian are synonyms defined as:

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

eternal (adjective)	aeonian (adjective)
tiresomely long; seemingly without end	of or relating to a geological eon (longer than an era)
continuing forever or indefinitely	continuing forever or indefinitely