Turtles are water based animals. Many people call tortoises "turtles". Tortoises are land based animals. Turtles must have a large body of water to live in, but they do spend time outside of the water to bask in the sun, lay eggs, dig for food and other turtle activities.
There are some rules to be aware of when purchasing turtles. It is illegal to buy a turtle or tortoise that is under four inches - you can find them that small BUT DO NOT SUPPORT that seller. There are certain species that cannot cross state lines - for example a red ear slider can be purchased in Kansas but cannot in Missouri without permits and proof of being CAPTIVE BREED. So if you live close enough to buy one in Kansas but live in Missouri - if you do it have your papers in order.
Tortoises
Tortoises are land animals. Smaller species of tortoises can be housed indoors in large plastic bins, stock tanks or small plastic pools or even young large species can be housed that way for a while. Some tortoises get extremely large and must have adequate space to thrive. They also do better in enclosures that have solid walls not a glass tank. Most tortoises live over 40 years. Tortoises need lots of greens, hays, vegetables and some fruit.