Yeah your question isn't quiet phrased right, but the literal answer to that would be "no difference". Rick phrased it the way you were thinking. Basically (and this is me learning here the last few months) is that a FOWLR
tank doesn't have corals or inverts etc in it. Why a FOWLR
? Lots of fish eat inverts and corals in the "real world" so you have to decide what you want in the tank.
The first question id "do you want to keep real coral" in the tank? The next question is what type of fish do you want to keep with the coral. If any of the fish on your wishlist aren't "reef safe" or "reef compatible" (which you can find out with a few simple Google searches) you have a decision to make.... would you rather have that fish or all the corals.
For example, I REEEEAALLLYYY wanted a Humu Picasso more than any other fish but I wanted a reef because of all the other life involved. So I decided to go reef because the triggers aren't reef friendly. Dr F&S has a nice overview of their fish to help you out Saltwater Aquarium Fish for Marine Aquariums: Humu Picasso Triggerfish