Angular controller this vs $scope.

app.js

'use strict';

var app = angular.module('app', []);

app.controller('AppCtrl', function ($scope) {

  this.foo = 'bar';
  $scope.hello = 'world';

});

app.directive('app', function () {

  return {
    restrict: 'C',
    controller: 'AppCtrl as app'
  }

});

angular.bootstrap(document.getElementById('container'), ['app']);

index.html

<div id="container" class="app">
  
  <input type="text" ng-model="hello">
  <p>{{hello}}</p> <!-- world -->
  
  <input type="text" ng-model="app.foo">
  <p>{{app.foo}}</p> <!-- bar -->
  
</div>