[norton]

A euro may be theoretically worth the same across the continent, but in fact you can buy far more with a euro in, say, Portugal than you can in, say, the Netherlands.

Or:
A dollar may be theoretically worth the same across the continent, but in fact you can buy far more with a dollar in, say, Georgia than you can in, say, California.

[Vanders9]

Yes that’s true, but its much more marked in Europe. I mean you would expect variations inside the US because of things like local taxation, and real estate, and housing costs, but the differences in Europe go as far as very basic commodities, like food, which can cost 2-3 times more in some countries than in others.