：））看来我是没分清,Google后小结如下

http://www.sandiegozoo.org/animalbytes/t-turtle.html
http://www.diffen.com/difference/Tortoise_vs_Turtle

1 Names are used differently in other parts of the world. For instance, in Australia only sea turtles are called turtles–everything else is called a tortoise! ：）

2 Turtle (20-40 years lifespan)— Spends most of its life in the water. Turtles tend to have webbed feet

3 Tortoise (80-150 years lifespan) A land-dweller 旱龟

4 Terrapin (American Eng?)— Spends its time both on land and in water, but it always lives near water. The word terrapin comes from an Indian word meaning "a little turtle.”