Instance Name VS Symbol Name

programming flash
1

I’m just starting out with flash and I have a pretty simple question (I think) …

I was looking at this tutorial: http://www.kirupa.com/developer/mx2004/menu_with_slider2.htm

and… .

I was wondering why would we reference a symbol name sometimes and then other times we would reference a instance name.

For example, in the example above in the actions layer we have this:


 
// slider_mc is your movie clip's name, not the instance Name. 
slider_mc.onEnterFrame = function() {
	this._x += (xMove-this._x)/easeSpeed; 
}

Then in the button press events we have this:

 
on (rollOver) {
  // slider - Movie Clip's Instance Name. button_1 - buttons Instance name. 
  slider.xMove = button_2._x + Pad****t; 
}

The first one uses the symbol name, the next one uses the instance name.

Why does this happen? Why cant we reference everything by the instance name? Can we?

I’m just looking for a simple explanation of how both of them work in relation to each other so I can wrap my head around this.

Thanks!