Proterozoic eon vs Proterozoic aeon

Proterozoic eon and Proterozoic aeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
Proterozoic eon	Yes	No	No	No
Proterozoic aeon	Yes	No	No	No

As nouns, Proterozoic eon and Proterozoic aeon are synonyms defined as:

Proterozoic eon and Proterozoic aeon: from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms

Other synonyms of Proterozoic eon include Proterozoic.

Proterozoic eon (noun)	Proterozoic aeon (noun)
from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms	from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms