Hello there! The confusion between Clawed and Dwarf frogs is actually quite common, and definitely isn't a stupid question. Obviously, like you said; Dwarf frogs would be the species with the webbed feet. But to just to make sure, I have a few more questions. Are their eyes flatter or somewhat more protruding? Clawed frogs will have the latter. How big are the frogs? Dwarf frogs won't grow much more than an inch and a half at the most, while Clawed frogs will grow to be at least a little larger (which like you stated, will require a bigger tank) and usually are a bit 'chubbier' in the waist area as well; of course, that isn't a perfect indicator either. Last thing - they aren't albino, are they? You probably would have stated that, but that would instantly make them Clawed frogs. In general though, it wouldn't be the first time pet stores have batched them together simply because of similar looks as youth. If you have any more questions, don't hesistate to ask (and if you have any, pictures would obviously make the process just a tiny bit easier; but no pressure).