The only difference is a huge difference though. Pay once for a game that you can access anytime versus paying continuously for the rest of your life to keep access to a game.
Some games are not worth keeping access to and subscription may end up being cheaper, but it is trading one benefit for another.
Glad to see a one time fee for ad removal, but it's pretty steep. Maybe when the app matures and is not in beta I'll consider it. Thanks for the update!