Movie clip vs graphic

You probibly get this question alot but I did a search on the forum and couldent find anything usefull. My question is what is better to and in what situation?

I have been having one problem that maybe swtiching to Graphics can help:
I’ll draw something full screen, symbolize it (as a MC) and then shrink it to size, but the lines shrink too. I dunno if this makes any sence but my main question is about the movie clip vs graphic.

There really is no difference between the 2.

The only reason I can think of to have a graphic symbol is so that you can turn an imported pic (or drawn one in flash) into one so you can use _alpha and whatnot on it.