You are quite right, I was mixing them up, but it is actually the same principle behind both.
This is new functionality of Chrome with the Windows support for PWA’s mixed in, and PWA apps actually have the same status as other installed apps and show up in the Applications menu on Windows just as they do in Android. And you can always pin their shortcut to the Start menu too.
Try this with the D&D forum and be amazed too (works both in Chrome on Windows and Android)
Edit: Oops, I spoke too soon: it seems that the D&D Discourse version is too old to support this on Windows, but it works on Android.
We are on version 2.3.0.beta5 here and the latest version is 2.4.0.beta6, maybe it is time for an update?
Note: while Discourse builds are labeled “beta” they are actually the most stable builds and are more current with features and security fixes than “stable” releases (but with an occasional bug too, which is fixed extra quick by the amazing Discourse team.