This question is more straightforward than it seems. The confusion comes in using the term “poetry” as separate from “prose”. The opposite of prose, however, is verse, not poetry.
Once, in teaching an introduction to poetry class, I started with 70 definitions of poetry I’d taken from different websites. I then gave the one definition of verse every source agrees on: metered language. Verse, as an art of organizing meaningful sound, has as much in common with music as it does with prose or common speech; and music is metered into bars & time signatures, etc. So verse is metered in iambs, trochees, etc.
An easy, quick way to state it: the basic unit of prose is the sentence, a unit of meaning (as organizing phrases into sentences into paragraphs into chapters into volumes… is done mostly to organize the meaning the author is trying to convey).
The basic unit of verse is the line: a unit of sound. The organizing principles are accent, tone, number of syllables (like beats per measure in music) or repetition ((like coda or chorus or theme in music).
Ignore what most people tell you about free verse. When free verse was first coming into use in the 19th & early 20th centuries, most people still read & knew verse. Everyone knew the term was intentionally oxymoronic. “Free” is not “verse” and “verse” is not “free”. Now, so few people read or think about verse, it is common to think free verse has no rules. No. That’s incompetent verse. “Free verse” is still metered, just more loosely, with more “substitutions” than verse usually has.
Bad prose writers who think they are writing verse also think the line break is just another type of punctuation, a weird way to add a comma. But hacked-up prose is not verse.
As for “poetry”, again, 70 definitions and counting. The word was taken over by people who never did or will never read a book of competent verse in their lives.