era vs geological time

era and geological time both are nouns.

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

As nouns, geological time is a hypernym of era; that is, geological time is a word with a broader meaning than era:

era: a major division of geological time; an era is usually divided into two or more periods
geological time: the time of the physical formation and development of the earth (especially prior to human history)

Other hypernyms of era include geologic time.

era (noun)	geological time (noun)
a period marked by distinctive character or reckoned from a fixed point or event	the time of the physical formation and development of the earth (especially prior to human history)
a major division of geological time; an era is usually divided into two or more periods