Phanerozoic vs Phanerozoic aeon

Phanerozoic and Phanerozoic aeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
Phanerozoic	Yes	No	No	No
Phanerozoic aeon	Yes	No	No	No

As nouns, Phanerozoic and Phanerozoic aeon are synonyms defined as:

Phanerozoic and Phanerozoic aeon: the period from about 540 million years ago until the present, a period when abundant life existed

Other synonyms of Phanerozoic include Phanerozoic eon.

Phanerozoic (noun)	Phanerozoic aeon (noun)
the period from about 540 million years ago until the present, a period when abundant life existed	the period from about 540 million years ago until the present, a period when abundant life existed