E3 2011 Build
Title Screen
Out of the many differences between this and the final game, the title screen had a very similar design to the ScareScraper loading screen, specifically when the camera moves up a floor but in this case, the camera would go into the ground. In the final* build, the design was ultimately scrapped for a simple black background possibly because Next Level Games thought it wasn't spooky enough.
E. Gadd's Lab
In the early lab, 5 monitors were present instead of 3. Each monitor had a different design and seemingly early Vault and Scarescraper pictures. The textbox was positioned and scaled differently and the "Press START To Skip" text was under it.
The build also had an early "Pixelize Out" animation. Additionally, you can see the Vault in the back.
Loading Screen
In this build, there was no representation of the portal Luigi used to go to and from E. Gadd's Lab. It was simply the window illustration used on the final build's boot-up loading animation.
Below is a video of a GIF showing what this loading screen and the "Pixelize In" animation look like.
Luigi's Mansion 2 — Loading + Pixelize In — E3 2011
Gloomy Manor
[TBA]
[TBA]