When I have a point to make, I write prose; when I have a sound to make, I write verse. This is a distinction based on ends. There is another distinction to be made, which is based on means.
Historically, poetry included what is today the domain of prose: storytelling (epics and ballads across cultures), screenwriting (back then it was stage writing), the religious treatise or philosophical dialogue (cf. the Bhagavad-Gita), even agricultural tracts (Hesiod, Works and Days) and meteorological textbooks (Aratus, Phaenomena). Similarly, the composition of verse has included, and can include, the composition of prose.
I don’t mean the “prosaic” and the “poetic,” with largely bygone connotations of dullness/mundanity and elevation/emotionality. Prose, considered mechanistically, is the composition of sentences; the poet, however, is composing both sentences and verse lines, simultaneously. Frost wrote of “sentence sounds,” and Pound believed poetry should be “at least as well written as prose.” These well-known dictums hint at the warp-and-weft nature, in poetry, of soundly structured sentences and sonically structured lines. The poet who allows sentence-composition to dominate will tend toward prolixity and “plodding” verse; the poet who allows line-composition to dominate will tend toward fustian, “gassy” work, weak on meaning.
Not that all dual-principled poetry has to sound like “Birches”; a lot of variation is possible, from the couplets of Pope’s Essay on Man, whose epigrammatic flair is perpetually threatening to atomize any argument into a succession of pithy two-liners, to the shaped quatrains of Dickinson, to the superlong verse paragraphs of Milton, the secret of whose idiosyncratic style is that he writes, using English verse lines, not English sentences, but Latin ones.