Tortoise or turtles

I have always referred to my red eared sliders as turtles and in all the years of owning and keeping red eared sliders I had to take one to a vet for the first time. I was concerned about one turtle that looked a little bloated to me so I took it in to have it checked out. Turns out she is alright and very healthy. While at the veterinarians office I was told that Ethel was a tortoise and not a turtle. Turtles I was told have a hinged shell that can close when the turtle pulls itself in for protection tortoises do not have a hinged shell and their shells are formed differently. I was always told turtles were aquatic and tortoises were non aquatic. I do take my red eared sliders out side when the weather permits so that they can get plenty of sunshine and fresh air. They eat pelleted Aquatic turtle food and fruits vegetables and berries. Right now I have 4 of then and they are named Fred, Ethel, Ricky, and of course Lucy.

This is Ethel