Fallout – How to count and group items on a line in the Fallout 4 Contraptions DLC

The Fallout wiki has an extensive list of known Vaults, as well as their purpose. Each vault description is backed by in-game material you are suppose to look for, but it does appear to confirm that there are no other vaults to be found as of yet.

• Vault 75: Vault 75 is an experiment in improving the human genome. It appears these tests were carried out using selective breeding, genetic modification and hormonal treatment. The test subjects have their growth accelerated, and at 18, are "disposed of". It is suggested that in certain situations, such as for the purpose of replacing research staff, exceptional candidates may have been used for other means.

• Vault 81: Vault 81 is a testing facility involving antibodies, disease and radiation. Vault 81 was under express orders to not evacuate under any circumstances, unless an official "all clear" was issued. In the event of an evacuation, it is suggested that the overseer would order the 'dweller section' to be mass-incinerated, including the dwellers.

• Vault 95: Vault 95 is a social experiment on isolation and drug addiction. All dwellers were drug addicts, and the experiment started pre-war.

• Vault 111: This is the vault our hero comes from, and was a test in cryogenics and long-term suspended animation.

• Vault 114: Vault 114 was another social experiment, where the inhabitants consisted almost entirely of upper-class society. The living conditions of the vault was advertised as highly luxorous, but in reality, it was the exact opposite. The overseer was chosen from the general population, and the interview process favored qualities such as no leadership skill and issues with authority. The purpose is listed in a terminal; "By taking away the luxury and authority these groups saw in surface life, we hope to study their reactions in stressful situations."

That seems to be the only difference. Items with a green trim can be picked up, moved, and placed in the settlement, or stored in the workbench for later use (note: it seems you can only store items that you can build yourself from scrap. Some items can be moved/placed and functionally used, but not stored, such as white picket fences). Items with yellow trim are simply for salvaging materials, and their names occasionally imply this, as they are often "ruined" items (ruined house, broken toilet). Yellow items are also not movable in workshop mode, which also supports that they don't have any real use in the settlement.

It seems safe to scrap anything with a yellow outline, with maybe a couple of exceptions. If you scrap a container (such as mailboxes), you might want to make sure it is empty first, or you'll have to retrieve the contents from the workshop inventory later. Or, perhaps, if you wanted to keep any trees that remain upright in the settlement, don't scrap it for wood.