another question on wattage

Hi all,

Thanks for the clarifications with my question about energy saving bulbs and wattage.

And while we are still on the subject, I would like to ask one more related question...

I once bought a fixture made in Poland (I live in the US). The seller told me I can use 60W bulbs. The fixture turned out to be marked for use with 75W bulbs, and there was a sticker on each socket telling me to use 40W bulbs.

I use 40W bulbs to be on the safe side, but...

What is the issue here? 220V versus 110V? Or something else?

Thanks, Arkadiy