heroic meter vs heroic poem

heroic meter and heroic poem both are nouns.

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

As nouns, heroic poem is a hypernym of heroic meter; that is, heroic poem 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
heroic poem: a long narrative poem telling of a hero's deeds

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

heroic meter (noun)	heroic poem (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