Prose and poetry are different literary genres. It is true that poetry can have a definite meter. For example sonnets have fourteen decasyllabic lines and they are written in iambic pentameter where a rigorous rhyme convention has to be followed. However, there is free verse and other types of poems which do not follow a specific scheme. On the contrary, prose does not use a specific meter, it is a natural flow of speech in written form. Accordingly, the characteristic that distinguishes prose and poetry is the metrical structure.
