…asks reader Adam. Great question. The difference is that one term sounds more appealing than the other. In practical terms, they mean pretty much the same thing. However I’d hasten to add that if you’re planning to make your own cultured butter it’s always better to “spoil” your own milk or cream with a culture you know is safe rather than to take a chance on a dairy product that’s inhabited by God-only-knows what. For there are quite a few types of microbes capable of growing in milk or cream and not all of them are harmless.
Truthfully I’ve been known to make cultured butter out of cream that’s soured on its own in my refrigerator, but in general I strongly advise that when you set out to ferment dairy, you inoculate it with a heavy dose of a known commodity, like store-bought buttermilk, sour cream or yogurt. A tablespoon or so per cup is usually enough to crowd out anything else that might consider making a go of it in the fermentation bowl. I should also add that once you’ve achieved your fermenting goal, you refrigerate the finished product, again, to discourage any adventurism by bugs from the wrong side of the tracks.
And of course, should anything you ever ferment give off a funky odor or exhibit a strange color (blue, green, pink), take no chances. Throw it out.