era vs time period

era and time period both are nouns.

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

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

era: a period marked by distinctive character or reckoned from a fixed point or event
time period: an amount of time

Other hypernyms of era include period, period of time.

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