What is the meaning of xs:mixed without elements?

Question

I got the following XSD bit from a customer. It is part of a legacy schema that spans over dozens of files.

Answer 1

It means that you have an element named stateProvinceName that has one or more attributes (as defined by xml:attlist.global-attributes) whose content is a string. As is, it's no different from the structure that you recommended.

Their potential difference, however, is their extensibility, as @Michael Kay noted.