In keeping with tradition Samsung once again introduced two hardware variants of its flagship Galaxy S9 phones. Most of the world gets units powered by Samsung's own Exynos 9810 chip, while US and China receive Snapdragon 845 chips instead. That's been the case for a few years now and with the previous generation - the Galaxy S8 duo and the Galaxy Note8 - the Exynos chip seemed to have more processing power if not much different real-life performance. Spoiler alert - this time around, however, the Snapdragon 845 flexes a bit more muscle overall, compared to the Exynos 9810...
Source: https://www.gsmarena.com/samsung_galaxy_s9_performance_and_battery_standoff_exynos_9810_vs_snapdragon_845-news-30430.php