Start Script. This is the script that runs at the beginning of the game as a cutscene. This is where you define all your game variables ect and where you load your first room.
Main Script.
The Main Script is a looping script that runs all the time the game is running. It will be processed 50 times per second unless delayed by a wait command. Scriptfunctions can do the same but can be turned on and off..
Transition. The effect that is used for a transition from one room to another. Can also be changed with setscreenchange during the game.