References and Further Information: 1  Morrissey, J.F. and J.L. Sumich. 2012. Introduction to the Biology of Marine Life (10th Edition). 2  University of California Museum of Paleontology. Bilateral (left/right) Symmetry.
A lot of things. For one, Whale sharks are fish and use gills to breathe. Blue whales are mammals. The blue whale is also bigger than the whale shark. The tail structure is also different if you watch the whale shark swim, it uses its tail in a side to side motion while the blue whale uses a up and down movement.
By Jennifer Kennedy. Whale sharks are the world's largest fish. Description: While its name may be deceiving, the whale shark is actually a shark (which is a cartilaginous fish). Whale sharks can grow to 65 feet in length and up to about 75,000 pounds in weight. Females are generally larger than males.