Specifically, the iPhone X A1865 uses the Qualcomm MDM9655 Snapdragon X16 LTE modem while the iPhone X A1901 has the Intel XMM 7480 modem. You can check out my previous article to understand more about differences among iPhone X models. Basically, the Qualcomm modem is more superior and I guess most people will prefer this option because it covers more cellular bands and the performance of Qualcomm’s chips has always been better than Intel’s.
Just like last year’s iPhone 7 / 7 Plus, the iPhone X sold as Verizon and Sprint models is the “better” iPhone with the faster chipset. It’s unfortunate that Apple throttled Qualcomm’s Gigabit LTE to match Intel’s slower version. As of now, Qualcomm is the only provider for Gigabit LTE.