American butter is legally required to be at least 80% milkfat. That number comes from an act of Congress in 1923.
Most American commodity butter sits right on that number, because the other 20% is water and water is cheap. European and European style butters run 82 to 85%.
2 or 3 points sounds like a rounding error. In a restaurant it is not. Less water means pastry browns instead of steaming, laminated dough holds its layers, and a pan sauce takes the butter without breaking.
European style is not a regulated phrase here. It means whatever the brand wants it to mean, so read the number on the panel instead of the words on the front. Plugra is 82% and it is made in America by Dairy Farmers of America. Kerrygold is Irish and also 82%.