To put it simply, a poem can be untitled, but words must have epigrams. Fill in the words with a fixed format of an epigram. The number of words in each sentence varies widely, which can be the same or different, just like the lyrics of our popular songs today.
And poetry, modern poetry, that is, metrical quatrains, each sentence must be of the same length, and there may be ancient miscellaneous words, that is, long and short sentences, but generally speaking, every sentence of mainstream poetry is the same, except that several sentences with different words may be added between these same sentences. Of course, there are several other poetic styles, such as Baota poems with one to ten words per sentence, but these things are basically word games, and the number is rarely negligible.
Generally speaking, the essence of poetry is like a composition arranged by a teacher, and words are like popular lyrics in ancient times.