It is the habitat that mainly differentiates a tortoise from and a turtle. Tortoises can be found in deserts, grasslands, or forests. On the other hand, turtles live in an aquatic environment. They can be found in oceans, swamps, freshwater lakes, ponds, and streams. In the United States, the term 'turtles' is generally used for the freshwater, marine, and most land Testudines. The species that are completely terrestrial are referred to as tortoises.