epoch vs time period

epoch and time period both are nouns.

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

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

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

Other hypernyms of epoch include period, period of time.

epoch (noun)	time period (noun)
a period marked by distinctive character or reckoned from a fixed point or event	an amount of time
a unit of geological time that is a subdivision of a period and is itself divided into ages
(astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded