I believe when you buy it on itch for $10, you're getting the next episode ahead of the free version AND all future updates.
With the Patreon version, you would have to re-subscribe every month (hence why it's a subscription) to get the most up-to-date version, which seems to be 2 episodes ahead of the free version as opposed to 1.
So yes, you would get a newer version of the game for the same price or cheaper up to the first two months, but you would have to keep paying beyond that to continue getting the most recent release.
I'm not a dev and I don't sub to their patreon so idk the full details, but I believe that's how their pricing model works. Hope it helps.