It makes no sense comparing US and EU prices directly, as the former are always shown without VAT (which varies state from state), and in the latter the VAT is included (which is specific to each country).
Also, price will fluctuate even across EU countries, on account of different VAT taxes in the individual member states, so that Apple "keeps the same digits" it is simply not true, as a rule:
iPhone X 64GB USA(no VAT): 999$ https://www.apple.com/us_kiosk_5000012/shop/buy-iphone/iphon...
iPhone X 64GB Italy (VAT 22%): 1189€ https://www.apple.com/it/shop/buy-iphone/iphone-xs
iPhone X 64GB Spain (VAT 21%): 1159€ https://www.apple.com/es/shop/buy-iphone/iphone-xs
The only way to compare them is to remove VAT, for example in the case of Italy:
1189/(1+0.22)= 974€ -->> 1100$ (current exchange rate).
So, there is about 10% difference, which could be (partly) accounted for due to the different warranty requirements in EU.
EDIT: Fixed math