Octopus vs Jellyfish The difference between octopus and jellyfish can be explained in terms of their anatomy and physiology. Octopus and jellyfish are aquatic invertebrates. Because of the different anatomy and physiology of these two organisms, they are categorized under different phyla. Octopus is categorized under Phylum Mollusca while Jellyfish is categorized under Phylum Cnidaria. […]