You may have noticed that there are a few dusty old threads way down at the bottom of the group here (I can't believe you managed to scroll that far). The threads are divided up into two different folders: "Revive a Dead Thread" and "Archive".
Revive a Dead Thread contains older discussion threads that haven't seen much use recently. As the title implies, however, these threads can be "revived". If threads in this folder receive a new post, they will be returned to their original folder with the more actively used threads at the top of the group.
Archives, on the other hand, are old staff announcements, informational threads, etc. that we no longer have a use for, but would like to save, just in case. These threads are closed to all new comments and cannot be "revived". They've taken up permanent residence in the Archives folder.
Revive a Dead Thread contains older discussion threads that haven't seen much use recently. As the title implies, however, these threads can be "revived". If threads in this folder receive a new post, they will be returned to their original folder with the more actively used threads at the top of the group.
Archives, on the other hand, are old staff announcements, informational threads, etc. that we no longer have a use for, but would like to save, just in case. These threads are closed to all new comments and cannot be "revived". They've taken up permanent residence in the Archives folder.