Rays and twins are both types of fish, but they are quite distinct. Rays belong to the superorder Batoidea, characterized by their flattened bodies, wing-like pectoral fins fused to the head, and ventral gills. They are typically bottom-dwelling and use their flattened bodies to glide along the seabed. Twins, on the other hand, are simply two individual fish born at the same time from the same mother. They share no specific biological characteristics beyond this shared birth event and can belong to any species. Essentially, "rays" refers to a specific group of fish with unique anatomical features, while "twins" describes a specific reproductive outcome that can occur across many fish species.