2. The difference between regular poems and quatrains is mainly in the number of words, four quatrains and eight quatrains. Quatrains, also called "truncated sentences", generally rhyme as one, two or four sentences (except special ones). The quatrains may or may not be antagonistic. And the neck couplet of metrical poetry must be a antithesis. Both metrical poems and quatrains require even tone, and metrical poems with more than eight sentences are called rhythm.