Sea turtles (penyu) terrapins (tuntung) and tortoises (kura-kura)

Turtle is a general term given to  

1. sea turtles (penyu),  
2. terrapins (tuntung) and  
3. tortoises(kura-kura). 

The main difference of these turtles are that sea turtles are salt water creatures, terrapins are freshwater creatures and tortoises live on land.