Widget : callback or event handler ?

Widget : callback or event handler ?

Hi, 

I've been studying how to create widgets with jQuery UI, and I'm now wondering what the difference between callbacks and event handlers is.

In the widget definition, I can write this line to trigger a 'change' event.

  1. this._trigger('change', 0, data);

And to catch this event, I can write one of those lines :

  1. $('.target').mywidget({
  2. change: function(event, data) { alert(data); } // callback to handle change event
  3. });

or 
  1. $('.target').bind('mywidgetchange', function(evt, data) { alert(data); });
    // event handler for change event

Am I right ? It actually seems quite similar... or am I missing something ?
When should I use callbacks ? And when should I use event handlers ?

Thank you in advance.

Clément