Final answer:
Protostomes develop a mouth before the anus, with spiral cleavage and schizocoely to form the coelom. Deuterostomes develop an anus before the mouth, with radial cleavage and enterocoely for coelom development.
Step-by-step explanation:
The difference between protostomes and deuterostomes is that protostomes develop a mouth first and then an anus, whereas deuterostomes develop an anus first and then a mouth. Protostomes, including phyla such as arthropods, mollusks, and annelids, exhibit spiral cleavage and the coelom forms by schizocoely, where cavities within clumps of mesodermal tissue converge to form the coelom.
In contrast, deuterostomes like chordates and echinoderms show radial cleavage and their coelom forms by enterocoely, where mesodermal pouches pinch off from the endoderm, fuse, and expand to form the coelom.