Waterspouts are tornadoes. The only difference is one is over water while the other is over land.
Not all waterspouts are created equal, though. Tornadic waterspouts are dangerous, and these form in severe thunderstorms.
Fair weather waterspouts are usually less dangerous and form on days of fair weather. These waterspouts form along a boundary of converging winds but are not necessarily associated with a thunderstorm.
Watch the video above to learn more about how different waterspouts form.