Effects

To define Echo is one line bouncing is an "echo." Many lines bouncing randomly is "reverb." The lines bounce around for more than a second, it's called reverb. If they bounce around for less than a second, it's Kosher to call it "room ambiance." If the radiating lines are in a room with no reflective walls, they wouldn't bounce back at all, and the room would be called "anechoic." By the way, my imaginary room is only two-dimensional. Real-life rooms are three-dimensional.
The radiating lines go in to the box and bounce back or reflect off the walls. Soon, there are so many lines radiating around in that imaginary box that they all collide with each other and become a random, jumbled mess. Eventually, the size of the lines and the number of them diminish.

CHORUS : A short delay time of about 100 ms, with minimal Feedback, and a little Mod Depth & Speed.

FLANGE : A very short delay time of about 40ms, with more Feedback, and anything from a medium to large amount of Mod Depth & a low Mod Speed

For a deeper CHORUS, add more Mod Depth and/or increase the Delay Time.
For a deeper FLANGE, add more feedback, and/or Mod Depth

Sound images are very similar to visual images. If you're in a large auditorium, but standing on stage right next to an actor's face, you will see every nuance of his face, pimples, pores and all. You will not see his whole body though, and you won't see him in the context of the rest of the stage or the room. If you move back to the tenth row, you will lose some of the facial detail, but you will gain perspective. If you move to the rear of the auditorium you'll lose all the detail of the actor's face, but you see the whole enchilada in perspective