Glossary
Volume GUID
The identifier Windows assigns to each volume it mounts, as in \\?\Volume{…}; it links MountedDevices to each user's MountPoints2.
The mount manager names every volume \\?\Volume{GUID}. The GUID is stable for a given device and partition on a given computer, and removable-volume GUIDs often end in 806e6f6e6963.
It appears in MountedDevices (next to the device path) and in MountPoints2 (per user), so it is the key that says which account mounted which device.