lifespan vs time period

lifespan and time period both are nouns.

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

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

lifespan: the period during which something is functional (as between birth and death)
time period: an amount of time

Other hypernyms of lifespan include period, period of time.

lifespan (noun)	time period (noun)
the period during which something is functional (as between birth and death)	an amount of time