On phonearena.com I read: "if you live in the US, you'll be getting the quad-core Snapdragon 820 processor. If you live elsewhere, however, you'll be treated to an Exynos 8890—an octa-core chip."
So it seems you're talking about different phones with different processors. Either your source is wrong or you read it wrong.
I have a question about the platform of galaxy S7. As I read it contains two chipset 1)Qualcomm MSM8996 Snapdragon 820
2)Exynos 8890 Octa. The second one is a modem, while there is modem inside Snapdragone 820. why it contains two chipset?