It is hard to define biblical poetry. It is often marked by parallelism, but not always. Thus, many are beginning to see prose and poetry on a continuum, with distinctions being fluid, not absolute. Poetry tends to make greater use of parallelism, imagery, etc. While prose represents a certain departure from normal speech patterns, poetry departs even further.
Poetry is more self-consciously structured.
Higher level of literary artifice. Major conventions are terseness, parallelism, and imagery. Terseness Hebrew poetry is short and to the point. Cola of poetic passages tend to be equal in length. Ellipsis intensifies the terseness of the poetic line.