would it be safe to say that a fluke (summer flounder)'s eyes are on the 'starboard' side of his head and a winter flounder's eyes are on the 'port' side of his head so to speak??
Flounder have round type mouth without teeth to suck food in. Fluke have a hinged jaw with sharp needle like teeth that you don't want to get bit with. There is little chance to mistake the two if they have there head on.
Port or starboard I can't remember which one faces which way, but I know that there opposite.