Thank you for asking.
This is a demo but it's currently identical to the steam version.
Paid version will have more content than the free demo starting v0.9 at which point the price of the game will increase a little.
It may sound confusing but here's a post explaining it in a bit more detail :
https://store.steampowered.com/news/app/831110?emclan=103582791464677531&emgid=3...