In the case of storage and servers, redundancy usually maps to uptime and availability. Think RAID or HA. Copies are distinct copies. If your RAID catches fire

In the case of storage and servers, redundancy usually maps to uptime and availability. Think RAID or HA. Copies are distinct copies. If your RAID catches fire, you want a copy that's somewhere else. Think external drive. In terms of backups, while you might want redundancy for availability, you want distinct copies in separate places ideally. So that if your building catches fire and takes your RAID, at least you have a copy somewhere else. A lot of these copies aren't in real time. That's what makes them an easy backup solution. A backup is a snapshot that allows you to go back to a point in time and see/recover things. Redundancy won't protect you against someone deleting their home folder. If the copies are in real time, that's gone too. So, copies aren't always backups and a backup isn't always a copy.