“Sea bass” is largely a useless term–it covers so many unrelated fish species that you’re better off just ignoring it. For example: there is one species, called the Mediterranean sea bass. The Italians call it branzino, and the French call it loup de mer. There is another fish, called the Chilean sea bass, that has no relation to the Mediterranean sea bass whatsoever (other than that it’s a also, you know, a fish.) The term “Chilean sea bass” is a marketing gimmick for the fish; itstrue name is “the Patagonian toothfish”. Properly cooked, branzino has a buttery flavor and a silky texture; Chilean sea bass is thicker, moister, and sweeter.
Advises butterfly, learn the latin names of the fish that you like and find a really good fish monger who you’ll trust to sell you exactly that fish. The problem with most fish sold in the US is that there are no real labeling laws, and the fish is sold in fillets which, while easy to use, make it terribly hard to identify what the actual fish-of-origin is.