lifespan vs hereafter

lifespan and hereafter both are nouns.

Word	Noun	Adjective	Verb	Adverb
lifespan	Yes	No	No	No
hereafter	Yes	No	No	Yes

As nouns, hereafter is a hyponym of lifespan; that is, hereafter is a word with a more specific, narrower meaning than lifespan:

lifespan: the period during which something is functional (as between birth and death)
hereafter: life after death

Other hyponyms of lifespan include afterlife.

lifespan (noun)	hereafter (noun)
the period during which something is functional (as between birth and death)	the time yet to come
	life after death

lifespan (adverb)	hereafter (adverb)
	in a subsequent part of this document or statement or matter etc.
	following this in time or order or place; after this
	in a future life or state