Github pages is a commercial product by the company Github, which is defined as follows in the official website
GitHub Pages lets you turn GitHub repositories into websites that showcase your portfolio, your projects, their documentation, or anything else you want to share with the world.
As you understand from this definition is that Github pages is a hosting service for tech savvy people, or even hackers.
Stastic is built on top of this excellent product, so that you do not ever have to use it directly. Your data will be hosted on Github, Stastic do not store them, as explained in the section “who owns my data”.