Sweet Cream Butter
As its name suggests, this butter is made from pasteurized fresh cream, and unless it is specifically labeled "unsalted" it is typically seasoned lightly with salt. This is the most commonly produced commercial butter in America. Though it can be used for cooking, most bakers prefer to use unsalted butter in order to have more control over the amount of salt in the finished dish.
Unsalted butter is simply sweet cream butter that has no salt added. It is the go-to butter of choice for most bakers because it gives one more control over the final amount of salt in a recipe. In other words, if a baking recipe does not specify the type of butter to use, it is safe to assume it is unsalted.
European butters—which you may have seen in the dairy aisle under brands like Kerrygold and Lurpak—are distinguished by their rich, tangy flavor and ultra-creamy texture. That's because, while North American butters must contain only 80% butterfat to be sold commercially, their European counterparts typically contain 82% to 85%
Cultured butter is made by infusing fresh cream with same kind of live cultures that are used in yogurt before churning, which gives the butter a distinct tanginess and smoothness. European butter is usually also cultured butter.