StreetComplete works by asking you for more details about certain things that are already on the map. It seems like Every Door doesn't ask you specific questions but lets you add any details you like, and also add new points to the map, which StreetComplete doesn't let you do.
StreetComplete is meant to be usable by a complete novice. Every Door looks like it's for mappers who already have a bit of an idea of what's going on and want more control over what they can add to the map.
I just discovered this app today; that's my understanding as well. It's also easier to all kind of nodes; with StreetComplete we're limited to add shops with the dedicated overlay.
Also, compared to my previous editor of choice to add nodes (OSM Go!), it seems to offer a better source of background imagery. I can actually my local government imagery source (swisstopo) instead of mapbox.
It's been submitted though: https://gitlab.com/fdroid/fdroiddata/-/merge_requests/11955