It's different enough. They are notable enough for their own wiki pages. Analysts spend their careers studying individual states.

https://en.wikipedia.org/wiki/Economy_of_Texas

Maybe 'central bank control' is a reasonable grouping measure, but 'size of economy' is also reasonable. There is certainly more nuance than a simple ranking can model.

And the 'central bank' argument is muddied by the existence of the Euro and the particular economic struggles of countries like Greece.