How can I remove all items from my vault and save them in a backup vault

I'm trying to move my items somewhere secure so I can delete everything in my main vault. There is to much there including duplicates and more. I would then like to remove all my items from the main vault so none are there and then when I need one, go get it from the backup vault and move it to the main one. There were a bunch of items in the archive "vault" but not all of them. I created a vault and moved everything there. I checked and everything was there. I then went to the main vault and deleted everything. Then I went to t vault where I had saved everything. It was empty. The archive had a lot of items but not everything. It made me realize I don not understand vaults. At this point, I'm just confused and not sure what items I have left. I don't think everything that was in the main vault is in the backup vault, though a lot is. I tried to recover my old vault using Time Machine but to my chagrin found out it had not been operating since July. Where can I learn how vaults work. They are obviously not independent of each other. I can't figure out where my main vault is.