Debug Builds
Internal development "Red" builds of Milo/Forge engine games have extra features and usually come with symbols.
RND Overlay
This is an overlay that shows notifies, the DTA console and other various debugging features like the FPS counter and memory usage. The font used is rendered by the console using vectors defined by "../../system/run/config/rnd_font.dta".
Show Cheats
This menu shows a list of every cheat defined in the "config/cheats.dta" file and the value inside "config/CODENAME_version.dta" and the games code name. This menu seemingly got added for debug builds of Guitar Hero II's Xbox 360 port and got removed in Rock Band 4 debug builds and onwards.
Notifies
This will put error messages sent with "{notify}" or Debug::Notify on the screen using the RND Overlay. The Beatles Rock Band and after allow you to toggle how the notify is shown, toggling between overlay, modal and disable. Having it set to overlay will show the notify at the top of the screen without pausing gameplay. Modal will halt the game to show a screen with the notify message, the color of this screen has been blue, purple (Rock Band 2 Wii) and green (Dance central 3), Pressing any button (including analog stick movement) will leave the notify and continue the game.