epos vs poem

epos and poem both are nouns.

Word	Noun	Adjective	Verb	Adverb
epos	Yes	No	No	No
poem	Yes	No	No	No

As nouns, poem is a hypernym of epos; that is, poem is a word with a broader meaning than epos:

Other hypernyms of epos include verse form.

epos (noun)	poem (noun)
a long narrative poem telling of a hero's deeds	a composition written in metrical feet forming rhythmical lines
a body of poetry that conveys the traditions of a society by treating some epic theme