Precambrian aeon vs Precambrian period

Precambrian aeon and Precambrian period both are nouns.

Word	Noun	Adjective	Verb	Adverb
Precambrian aeon	Yes	No	No	No
Precambrian period	Yes	No	No	No

As nouns, Precambrian aeon and Precambrian period are synonyms defined as:

Precambrian aeon and Precambrian period: 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 aeon include Precambrian, Precambrian eon.

Precambrian aeon (noun)	Precambrian period (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