Are we comparing, country, population, size of region?

We often compare USA with China, but when it comes to european countries, it has to be EU?

This is an honest question, I couldn't care less about either region or gain anything financially or care about emotional internet points. I am not rooting for anyone, though I think predominantly western centric super powers is a bad idea.

But why this line of thinking and comparison, isn't it apple to oranges? Its a genuine question, despite being downvoted for whatever reason.