https://www.britannica.com/story/whats-the-difference-between-a-turtle-and-a-tortoise

What is a tortoise anyway? Is it just a fancy way to say “turtle”? Well, actually, there’s a meaningful difference between tortoises and other turtles. All tortoises are in fact turtles—that is, they belong to the order Testudines or Chelonia, reptiles having bodies encased in a bony shell—but not all turtles are tortoises. If tortoises are turtles, why not just call all turtlelike creatures “turtle”? Because if the animal you’re referring to is a tortoise, some wise guy is going to correct you every time.