geological era vs era

geological era and era both are nouns.

Word	Noun	Adjective	Verb	Adverb
geological era	Yes	No	No	No
era	Yes	No	No	No

As nouns, geological era and era are synonyms defined as:

geological era and era: a major division of geological time; an era is usually divided into two or more periods

geological era (noun)	era (noun)
a major division of geological time; an era is usually divided into two or more periods	a period marked by distinctive character or reckoned from a fixed point or event
	a major division of geological time; an era is usually divided into two or more periods