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.
The biggest fish in the ocean is the Rhincodon typus or whale shark. Despite their tremendous size and intimidating appearance, whale sharks are commonly docile and approachable. Please keep your distance, giving them the respect and space they deserve. Whale sharks can grow to. and weigh as much as 40 tons by some estimates! The largest reported whale shark was 20 meters, but it is uncommon to see them longer than 12 meters. They have broad, flat heads with short snouts and their backs have an interesting white, yellow, and grey checkerboard pattern.