I've never noticed one, but one difference (at least in the past) was that perfume in Europe was made with pure grain alcohol, whereas what they distributed in the US was made with denatured alcohol so that people couldn't drink it. I think the perfume oil was the same.
Some old Guerlain EdCs say "blended in the USA" or Mexico, because they only imported the oil and bottles, and then blended it with domestic alcohol and bottled (to avoid paying to ship all that alcohol across the ocean I assume).
Nowadays, I think it's all made in the same place the same way. I assume it simplifies their supply chain and manufacturing to keep it all in one place.