To explain the difference between lobsters and crayfish, they are both delicacies, but one is expensive and the other is cheap. Lobster belongs to shellfish and has advantages in terms of nutrition and hygiene since it lives in the depths of the sea, salty water, less pollution, and higher nutritional value than the river.
Also, Lobster is more popular with high-end hotels. It offers a wide variety of cooking methods, and there is no need to worry about parasites at all, as deep-sea species are uncontaminated.