Chordates are primarily animals with some very distinctive characteristics that possess a notochord that develops into the backbone, a dorsal nerve cord that is the spinal cord, pharyngeal slits that are a series of openings found immediately posterior to the mouth, an endostyle that is an internal groove found in the ventral wall of the pharynx and a post-anal tail for at least some period of their life cycles. These features characterize any animal as a chordate. They do not have spines; they just need to have a spinal cord, and generally it has four appendages that are in the forms of legs, arms, wings or fins. The Phylum Chordata includes more than 60,000 species with over 57,000 vertebrate species, 3,000 tunicate species and few lancelets. Animal groups in the chordate phylum include fish, amphibians, reptiles, birds, and mammals.
Vertebrates are a subgroup of the chordates, this means that all vertebrates are chordates, but not all chordates are vertebrates. They are distinguished from other chordates by having a backbone or spinal columns, a brain case, and an internal skeleton. They have a muscular system that consists of paired masses, and a central nervous system. Vertebrates are the major group of the chordates in terms of the number of species, evolutionary sophistication, and many other aspects as well. The most important feature of the vertebrates is the well-developed brain covered by the bony structure called “skull”.
In conclusion, all the vertebrates are chordates, but not all the chordates are vertebrates. There are more vertebrates than non-vertebrate chordates. Clear cephalization is much pronounced in vertebrates than in non-vertebrate chordates. The vertebrates’ muscles are arranged in paired masses, but not in all chordates. Also, vertebrates have a spinal cord and a backbone, but not the other chordates.