I long thought that the main difference between US and French butter was that US butter was from fresh cream and French, from sour cream, maybe only slightly so

I long thought that the main difference between US and French butter was that US butter was from fresh cream and French, from sour cream, maybe only slightly sour. In the US, I get "unsalted" butter, sometimes recommended for dessert cooking, and sense that it has a little more flavor than salted butter, maybe is a little closer to French sour cream butter.