Again I've stumbled upon two tags which seem to describe the exactly same issue:
recovery (x22):
The Android recovery system is a bootable partition on an Android device...
recovery-mode (x75):
Android's recovery mode allows ROM flashing...
The only recognizable distinction to me is the viewpoint: file system ("partition") versus boot-mode. Does that justify separate tags? I'd say: let's merge them and make the then "empty one" a synonym to the other.
Remark: We also have data-recovery for recovering lost files. So for consistency, recovery-mode should IMHO be the (main) tag (also as it already holds the majority of questions), and recovery the synonym. I vote for a synonym as otherwise it will for sure turn up as a new tag sooner or later, referring to either the partition or the files/data.
