Stew is a form of Soup from the boiling method. Something that uses all three primary elements and a binder/sauce. Often the binder originates from simply blending a small amount of the ingredients in the pot. But noodles, dumplings, cooked grain and even flour and bean puree is usable for creating a weighty body to the stewform.
A stew usually has larger cut pieces than a loose vegetable style soup. Although they can both have the same ingredients, the stew almost always has a protein creating a balanced, single focus meal.