$.fn.extend or $.fn.myPlugin

$.fn.extend or $.fn.myPlugin

Hi,
I'm reading several Plugins and found following Syntaxes:
  1. $.fn.extend({
  2.      nt_modalbox: function (opts) {

  1. $.fn.nt_modalbox = function (opts) {
In my testings both did the same. Are they both just different ways to write the same thing?