The definition of poetry is nebulous.
It is differentiated from prose by an attention to sound, using
alliteration, rhyme, meter and assonance among other things to create
consonance, and an intentional layering of the meanings of the words
with symbolism and similarities, similes and metaphors, to create
depth of thought.
Often prose will employ these tools
too, but not to the same degree, though prose can be described as
lyrical or poetic. In fact, most good story writers are