I’ve heard people distinguish between a soup and a stew by the thickness of the broth. For example, I was watching an episode of Food Network Challenge one time and one of the contestants (a retiree in his seventies who had won in a previous challenge) prepared a faux she crab soup. One of the judges (supposedly an authority) said it wasn’t a soup because it was too thick; rather, it was a stew.

Now that was really mind-blowing for me. As far as I knew, it’s not the thickness that distinguishes a thick soup from a stew but, rather, the length of time that the meat or seafood, or both, and the vegetables are cooked together. Emphasis on together. When cooking the stew, the meat and vegetables are cooked together longer, often for hours.
Length of cooking time
But, come to think of it, even the length of time is a subjective standard. If meat and vegetables were simmered for less than an hour, it might be a soup. But if simmered for a minute over an hour, it’s a stew? Who makes the arbitrary distinction?
Thickness and clarity
If we go by common layman observation, a stew is usually thick and the sauce is rarely clear. A soup, on the other hand, is thinner and, in most cases, the broth is clear.
But these observations cannot serve as strict definitions. Some soups, like those made with roux or pureed vegetables (think potatoes, carrots or peas) are as thick if not thicker than some stews. And they aren’t clear either.
Order in which it is served during a meal
There are those who say that a dish is a soup if served ahead of the main course; it is a stew if served as a main dish. Whoa. In the Philippines, dishes like tinola and sinigang are soups that are served as main courses and, often, eaten with rice. Go figure.
It’s the intended use, dummy!
Given all that, I’ve come to the conclusion that whether a dish is a soup or depends on personal perspective. Never mind what the pretend-authorities on the Food Network say. I like the way that Eileen Goltz put it in her article on The Journal Gazette:
If you’re still confused as to the difference between a stew and soup, just ask yourself this question: If someone you love is not feeling well decide whether or not you’d say I brought you this (fill in the blank with whatever you’re considering making) to make you feel better. Truly, saying I brought you this stew for your cold doesn’t play as well as here’s some chicken soup.
There it is. It is the intention on how a dish is to be served and enjoyed that distinguishes a soup from a stew. I think I’ll stick to that definition. Not hoity-toity but still very wise.
Recipes to try
Thick soups:
Stews: