[pezezin]

Wait, what? We don't have middle names, we have "nombres compuestos". Sometimes you may drop part of the name, sometimes not, but you will never see a form with a field for the middle name like you see in English speaking countries.

[narag]

So different ways of calling the same thing and different UIs. But it's just given names vs. family names and a set of rules. I like Bulgarian ones most.