A drawn fish is a whole fish minus its internal organs. A drawn fish may still need to be scaled.
A dressed fish has had its organs, scales, head, tail, and fins removed. It's ready to be cooked.
A fish steak is a crosscut slice from a large dressed fish. Steaks do not need any special preparation before cooking.
A fish fillet is a boneless piece cut lengthwise from the side and away from the backbone.