heroic meter vs epos

heroic meter and epos both are nouns.

Word	Noun	Adjective	Verb	Adverb
heroic meter	Yes	No	No	No
epos	Yes	No	No	No

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

heroic meter: a verse form suited to the treatment of heroic or elevated themes; dactylic hexameter or iambic pentameter
epos: a long narrative poem telling of a hero's deeds

Other hypernyms of heroic meter include epic, epic poem, heroic poem.

heroic meter (noun)	epos (noun)
a verse form suited to the treatment of heroic or elevated themes; dactylic hexameter or iambic pentameter	a long narrative poem telling of a hero's deeds
	a body of poetry that conveys the traditions of a society by treating some epic theme