Proterozoic aeon vs Proterozoic eon

Proterozoic aeon and Proterozoic eon both are nouns.

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

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

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

Other synonyms of Proterozoic aeon include Proterozoic.

Proterozoic aeon (noun)	Proterozoic eon (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