It's x86; it works better for hardware accelerated video playback via VAAPI due to FOSS Intel drivers; because it's fully integrated out of the box, its total cost is a bit cheaper than an RPi, and as a single unit with no assembly, it's quite a bit faster to deploy.
I'm using these: https://www.amazon.com/MeLE-Fanless-Computer-Ethernet-PCG02/.... Works great with Linux, and has a very customizable BIOS.