The /org/freedesktop/UDisks2/drives/* objects

Objects with object paths starting with /org/freedesktop/UDisks2/drives/ all represent disk drives, typically physical disk drives. Such objects implement the org.freedesktop.UDisks2.Drive D-Bus interface and may optionally implement other D-Bus interfaces such as org.freedesktop.UDisks2.Drive.Ata depending on the drive in question.

A drive object should not to be confused with block device objects (which are used for low-level block devices the OS knows about). For example, if /dev/sda and /dev/sdb are block devices for two paths to the same drive, there will be only drive object but two block device objects.