(I could think of several, but there is so much overlap for all metrics I can think of that it almost makes the distinction academic.)
- Jake If you only spend 20 minutes of the rest of your life on economics, go spend them here.
The same distinction is made in Germany and Hungary, though the difference of the terms isn't commonly stressed. *Lunatic*, n. One whose delusions are out of fashion.
But I can see the advantages of your way of defining things.
In America, the term means the Middle Income Class, and the "Great American Middle Class" created as a result of the Great Compression of roughly 1936-1945 is only coherent when understood as a Middle Income Class.
And primarily composed of people, who living as workers in a low-wage economy, could never have aspired to the standard of living of those who would have been Middle Class in the UK sense before the Great Compression.
The great Republican political project of the last half century has been to exploit cultural and economic fault lines to fracture the politic expression of the GAMC in the New Deal Coalition. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.