Nah, it is the same game but in FullHD.
Usually the Free Version is in low res.
2.1.16 is an older version, so someone was kind and gave the Update code to the Dude who postet the game here
Havent read the Patchnotes yet. But technically you could play the HD version until you reach the end of 2.1.16. And then continue with the low res version 2.2.03
This does not count for Episode 1.
Episode 1 is a game for itself. But you can load savegames from it into Episode 2
Actually that's not true.
archedio Episode 2.1 016 is the first part of the second season. The dev calls them episodes not seasons though. It had 16 updates and and isn't updated anymore.
The dev decided to split Season 2 because the game was getting too big. The second part of season 2 has 3 updates so far (hence ep 2.2 v3). So you first have to play Episode 2.1 016 and then continue with the current build.
The comment above is correct about the two different versions. Each update has the standard version in 720p and the extra version in 1080p that also contains a couple of extra scenes. They are different patreon tiers. None of these versions are free though.
Yeah, it is kind of complicated and I'm not all all surprised that new players get confused.
Edit:
Goobercreek No, Episode 1 is the intro.
To simplify: Episode 2.1 016 is part one of episode 2 and is getting no more updates. The second part of episode 2 is still ongoing and is currently named episode 2.2 v.3.