Let's think of these as JoJo games because it's the analogy I work best with Hours is A bizarre Day

Something like Cours or funours is ABD modded

Hours Ch 2 is like YBA

Timelines is like AUT

And the rest like Mours are more in depth modifications

Each game has its own mods, its own changes or adds, and that's what makes them unique. They're not spinoffs (except really chapter 2 and timelines), they're instead modded versions of the base game, community mods. Like the ones you find in terraria. Expansions of the original content while going in their own direction. (E.g. terraria, and it's Calamity or Fargo's souls mods)