eternity vs face of the earth

eternity and face of the earth both are nouns.

Word	Noun	Adjective	Verb	Adverb
eternity	Yes	No	No	No
face of the earth	Yes	No	No	No

As nouns, face of the earth is a hypernym of eternity; that is, face of the earth is a word with a broader meaning than eternity:

eternity: a state of eternal existence believed in some religions to characterize the afterlife
face of the earth: the state or fact of existing

Other hypernyms of eternity include being, beingness, existence.

eternity (noun)	face of the earth (noun)
a state of eternal existence believed in some religions to characterize the afterlife	the state or fact of existing
time without end
a seemingly endless time interval (waiting)