Apparently differences in size depending on the Country of Origin

Had tried the shoe in size 8 in the store and found a bit too small. Then I ordered a number to me this shoe at Amazon bigger. When he was delivered, I had an "Encounter of the Third Kind". This shoe one size smaller (9) was much too small and I had to send it back, Country of Origin: China. Then I bought the same model in a shoe shop in size 9. And this model fits, Country of Origin: Vietnam. The difference between the two models in size 9 seems to be only in the origin country. Either I had now particularly unlucky and it was a bad design or it is actually the origin country.