No, but the terms are often used interchangeably. Cajun seasoning is a popular flavoring from Louisiana that is used to season meats and seafood, as well as soups and stews. Blackened is a cooking method that entails taking a Cajun-type rub and seasoning both sides of either chicken or seafood then searing it. You can use Cajun seasoning, both homemade and storebought, to make blackened chicken or seafood.