Dragons are might monsters known to fly, summon fire from their mouths, horde treasure, fight knights and kidnap princesses. In other mythologies Dragons are masters of Water, Weather, and symbols of Imperial Power. 

Now what are dinosaurs, big, sometimes enormous creatures of an age long passed. While past imagining of dinosaurs have them appearing as reptiles, modern day paleontologist theorize that many dinosaurs would've had feathers and are more closely related to birds than reptiles.   

Bibliography

Dragons: A brief history of the mythical, fire-breathing beasts

Wikipedia: Chinese Dragons. . . 

the Four-winged Dinosaur

National Museum of Natural History (a New View of the T. Rex)

Hollow Bones and perfect Respiratory Systems. . . 

Dinosaurs' Unique Bone Structure. . . 

https://www.unearthingtrex.com/pages/rex_traits.html

Physiology of Dinosaurs

Paleontologist's New Theory for Short Arms: Feeding Evolution

T. Rex Overview

the Quetzalcoatlus

from Dino to Birdie

T Rex's Speed (livescience)

T Rex's Speed (Smithsonian)

Speed of a Tiger