1, species: sea butterflies refer to a class of gastropods after the gill subclass of animals, usually with a transparent appearance, the body size is smaller, the largest not more than 5 cm. While the sea angel is a special kind of organisms of Gastropoda Posterior Gill Subclass, the form is similar to the floating jellyfish, the body is conical, the umbrella is very large, with banded structure.

2. External features. Sea butterflies usually have round shells, while sea angels do not have shells, its body is translucent, with an umbrella-like structure similar to jellyfish.

3, life habits. Sea butterflies usually live in shallow waters and like to float on the surface of the sea, while sea angels usually live in deep waters and have the habit of floating vertically.