Places that only exist for apps: store nominations, in-app events, public betas and app communities.
An open test is listed on Google Play, so anyone can join the beta. A good first link to share before the full release.
This one lives inside the store or an app community, so it only applies to apps. In the workspace, Groivo gives Google Play open testing its own App Store campaign link (ct=) and Google Play referrer, so downloads from it show up in App Store Connect and Play Console.