There is about a million (at least 😉 suspecies of the cod.
The two most common species of cod are the Atlantic cod, and the Pacific cod. They like it colder afaik. To read the full go here: https://en.wikipedia.org/wiki/Cod
Howto cook a cod?
you can steam it, fry it, bake it etc. I did not try to barbecue yet. And I probably would not make it sushi style.