The path is a description of how the object moves on the stage. Cast - a graphic, sound, animation, text, or Lingo script. Sprites on the stage use casts as their representation. A sprite can have only one cast as representation at any time, but a cast can be used by many sprites. Script - a program written in Director Lingo.
Scripts allow programming of interactive applications that react on user input.
Behavior - a script that has been attached to a sprite and that defines functions for events that the sprite may receive and act upon. Event - an event or message is the way how communication within Director works. One can send a message to a certain sprite or to the movie itself. If the sprite has a behavior associated with this message, this behavior function gets executed. User input is translated into events as well.