Also, what exactly is in the 0.16 demos content vs 0.15?
The version here is currently equal to Patreon version 0.18. It will get free updates every 3 months (meaning it will get 0.21).
The free versions on Patreon are just a demo and end before the first time you enter the portal.
To find information about what is new in each month's update you can go through our public post on Patreon.