The vault door under Structures > Doors is sort of a scaled down version of a Vault door, and is a reference to Fallout 1.
A lot of the new objects added are simply a clean version of the ones already on the game.
The new vault power conduit transfer power from and to vault structures, that do transfer power as if they already have wiring. This not only saves a lot of space and resources, but also allows for better looking structures, without needing to run wires all around.
pc The stairwells at "Structures > Vault > Domestic > Domestic - Stairwell" or "Structures > Vault > Utility > Utility - Stairwell" (the ones that go from one floor to another but changes direction inbetween) seems to be "broken", where the player can easily go up and down, but no NPCs are able to use it, simply ignoring that it's there. Generic settlers and even Overseer Barstow will often group at some random spot or simply stop at the beginning of the stairwell instead of using it. If they work at a level and their beds are located on a different level, where the only access is through that specific stair, they will often group all at the same spot and stay there when it's time for them to sleep, unless you fast-travel or "wait" on a chair or bed, making them teleport to their beds and get "trapped" on that floor. [verification overdue]
Different structures do not 'seem' to be broken, the snap fit connections simply do not exist. One cannot snap fit the super plush but different cross sectional Overseer apartment build to the main Atrium and having fiddled the main overseer circular Atrium hole to align with the main Atrium hole-or gap- one cannot then exit the room by any stairs since none will snap fit.One ends up with an isolated Overseer room overlooking the main Atrium as seen by visiting Vault 81 yet cannot snap fit any descending parts to get to the ground floor or any exit to allow entry or exit. The offending piece for connecting the Overseer apartment with OVERSEER WINDOW (314) to a lower level Security room with security desk and guard in the cave is STRUCTURES-DOMESTIC-STAIRWELL (209).or horizontally any DOMESTIC PIECE will not connect.