I'm not much of a reader of poetry, usually prefer fiction, but one respectable point of view is that metaphor is the main element of poetry, and that rhymes and meter and all else are secondary. There isn't really a hard line between prose and poetry. I 'found' a poem once in the clues and solution to a jumble-puzzle. But the intent of a poem signals that it's meant to be read with aesthetic attention, the way a book of fiction signals that it's not a history or memoir or something. I think the intent is all one can go by. usually.