Even as I resolve to become a more knowledgeable eater, any flatfish is vaguely interchangeable in my mind.
Halibut is the large tasty creature fishermen get all excited about, and sole - I know it mostly as that familiar harborside buttery main course, classier than a flounder. I remember hearing stories about different kinds of flounders and turbots being able to face each other, because their eyes are on the opposite sides. It's a bit confusing and if you try to keep track of which ones face which way, it gets complicated. These are flounders with some serious issues.
Shown here are just 2 examples out of numerous different kinds.
<-- "right-eyed" sole and "left-eyed" halibut -->
Both make good sashimi and sushi - karei (カレイ) and hirame (ヒラメ).
>Poached halibut, sweet and sour golden and red beets, citrus and extra virgin olive oil emulsion - Le Bernardin Restaurant, New York, NY
>Sole amandine, filet of sole with almonds and sun-dried tomatoes - Tempo restaurant, Alexandria, VA