How to open a .app which is inside the Contents/Resources/ of the script? I am trying to create a applescript that when I double click on it, the code activates an (or multiple) application/s from inside it. e.g. I just click on this script and it opens Photo booth and COD.
You can use path to resource to get the pathname of the .app file that's in an App's Resource folder, and then use Finder to open the apps, e.g.:

set appPath1 to path to resource "AppName1.app"
set appPath2 to path to resource "AppName2.app"

tell application "Finder"
    open appPath1
    open appPath2
end tell


Note: This method is for use from a AppleScript App's script that is run upon the AppleScript App being opened. If this is not what you're lookin for, then I misunderstood your question. If I did misunderstand, would you please clarify your question.