Poriferans are animals that have numerous pores (i.e., pori) on their body. Generally we know them as Sponges. They may be either marine or freshwater animals. They have a body fixed witha a substratum like rock, wood etc. Examples- Sycon, Glass-rope sponge, Hexactenellida etc . Food enters through numerous body pores (ostia) and undigested matterexits through the single big axial pore (osculum)
Coelenterates are animals which have a body cavity as their digestive system (coel- body cavity or coelom; enteron- gut). These animals have numerous cnidoblast cells (spine cells) on their body. These animals are also called Cnidarians (cnidi-spines or thorns). Examples- Hydra, Obelia, Aurelia etc. Food enters through mouth (also called Hypostome) and undigested matter exits through it also.