What is the major difference between vertebrates and invertebrates?

The major difference between vertebrates and invertebrates lies in their skeletal structures. Vertebrates possess a backbone or spinal column made of vertebrae, which provides structural support and protection for the spinal cord. In contrast, invertebrates lack a backbone and include a diverse range of organisms, such as insects, mollusks, and crustaceans. This distinction leads to significant differences in their anatomy, physiology, and evolutionary adaptations.