Phanerozoic eon vs Phanerozoic

Phanerozoic eon and Phanerozoic both are nouns.

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

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

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

Other synonyms of Phanerozoic eon include Phanerozoic aeon.

Phanerozoic eon (noun)	Phanerozoic (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