Precambrian eon vs Precambrian

Precambrian eon and Precambrian both are nouns.

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

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

Precambrian eon and Precambrian: the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago

Other synonyms of Precambrian eon include Precambrian aeon, Precambrian period.

Precambrian eon (noun)	Precambrian (noun)
the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago	the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago