Are there differences between the different country's editions of Cards Against Humanity?
Yes, I have both the US and the UK version. There are different cards in both editions. And there are cards with slightly different texts (for example Dear Abby in the US version and Dear Agony Aunt in the UK version).

And some names are different (Margaret Thatcher only appears in the UK version). The UK version also contains Scottish warriors lifting their kilts and pronouncing the names of Welsh towns.