Preloader - contentLoaderInfo vs enter_frame

Hi everybody this is my first post!

It’s a general question I hope this is the right place to ask it…

I’m wondering what the major differences are between these two styles of preloaders -

myLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, progressLoad);

vs.

stage.addEventListener(Event.ENTER_FRAME, progressLoad);

// Functions that handle progressLoad correctly etc…
//

I always use the first, but I notice that sometimes the counter isn’t consistent.
Could anybody please shed some light as to to pros and cons of either?