1. Difference in appearance: bull rays have a relatively long, cylindrical body with a short dorsal fin and a long, flattened tail; skates are relatively short, with a long dorsal fin and a short tail.

2. Difference in activity: Bull rays tend to live in the deeper parts of the ocean and usually do not enter shallow waters; rays tend to move along the coast and in shallow waters.

3. Difference in food habits: Bull rays are carnivorous, feeding on small fish and crustaceans, and have a wide range of activities; rays are bottom feeders, feeding on benthic invertebrates and small fish.

4. Difference in reproduction: Bull rays have ovoviviparous reproduction, covered with a layer of black skin; rays are ovoviviparous, with two egg shells in the uterus, carrying the embryo and yolk respectively.

Although there are differences in appearance and ecology, both cow-nosed rays and skates belong to the order Electrobrachium, and both are representatives of marine life, rich in nutrients, and both are in demand in the market, but are commonly found in different types of cuisine.