The number one difference I found during research is that turtles live near or in the water, and have adapted to be able to hold their breath under water. Tortoises, on the other hand, typically live in dry, arid places and have a special way of storing water, much like camels. In fact, if tortoises tried to wade out into water they would likely drown, because they cannot swim. Tortoises don’t have the streamlined shells and webbed feet that turtles do.
Also, turtles usually spend much of the year migrating so they can lay their eggs in shallow water or on the shore. Tortoises do not migrate at all. Also, while turtles have a varied diet including plant matter and smaller animals, tortoises diet consists of only vegetation.
The physical attributes of both are also quite different. They were developed differently based on the needs of the animal. For example, tortoises are slow creatures, unable to quickly escape from predators. Due to this fact, they have developed a large, dome-like shell that allows them to hide inside. Turtles, on the other hand, cannot hide in their shells. They are quick enough that they don’t need a special hiding spot; they can just run from their predators.
While turtles and tortoises are similar, there are also many differences. Both creatures have developed their own special attributes that help them survive.