Today, for the most part, yeah. It's a pretty meaningless distinction. But it used to actually mean something.

In the early modern period, it was used to describe people who were born peasants, yet had wealth and power to rival the nobility through - that's right, you guessed it - owning the means of production. "Middle Class" used to be a derisive term the aristocrats used for capitalists. If you presented the modern world to them, they'd say that we were ruled by the middle class -- and not in the cutesy way a liberal would mean.

It's about the size of the EU's population