The Supporter Pack DLC (available for Windows, Mac, and Linux) is a series of media files. It contains behind-the-scenes video clips, pictures, print-quality banner and poster images, and more.
The Supporter Edition of Muffed (and the Xbox Edition) comes with a few goodies in-game. These include a few extra maps for Battle Mode and Survival Mode, comics menu backgrounds, and extra hair types.
The Xbox Edition of Muffed has 3 primary differences. It does not have the Workshop, it has the Supporter Edition in-game goodies, and is limited to 8 maximum players (the Xbox has a maximum controller limit of 8). This Edition also integrates with Xbox features for things like achievements, cloud saves, etc.
Why does Xbox show me a "Permission Needed" popup?
The short answer: we don't really know exactly. Muffed does NOT collect any user info.
The long answer: This popup is required by Microsoft for any UWP-packaged app on Xbox. Because Muffed is a UWP app (as opposed to an XDK/GDK app), it is required for some reason. Muffed does not collect any user info at all. The extent of the "user info" that Muffed even has in memory is the current user's gamertag and gamer ID (used by literally every game on Xbox), which is used to integrate with Xbox Achievements, Rich Presence, and other basic Xbox-related integrations. We do not store/send/anything any user info of any kind. Outside of the Xbox API, Muffed doesn't even ping a server at all (because the Xbox version doesn't have the Workshop, and we don't even run analytics).
The Shareware Demo Editions of Muffed are exactly what they're called: shareware demos. This is a reference to older software and game demos sometimes referred to as "shareware". This term was used to refer to software that users are free to make copies of and hand out to their friends.
The Steam Editions of Muffed integrate several Steam features. These include achievements, Steam Input (which allows users to play with Steam Controllers, their phones, and define input assignments via the Steam Configurator), cloud saves, and Steam Remote Play Together (this feature allows you to play Muffed online with your Steam friends).
The Mobile Editions of Muffed feature touch controls, and only have single-player experiences of Muffed (Campaign and Survival Modes). Mobile Editions also have minor changes to a couple in-game bosses and such, to make them a bit more playable without access to twin-stick input.