Edit in JSFiddle

function demoCtrl($scope) {
  $scope.dest = [{
    id: 1,
    name: 'Peter'
  }]

  $scope.$watch('dest', function() {
    $scope.watchLog.push({
      log: '觸發！'
    });
  });

  $scope.$watchCollection('dest', function() {
    $scope.watchCollectionLog.push({
      log: '觸發！'
    });
  });

  $scope.$watch('dest', function() {
    $scope.watchtrueLog.push({
      log: '觸發！'
    });
  }, true);

  $scope.deepChange = function() {
    $scope.dest[0].id = $scope.dest[0].id + 1;
  }

  $scope.shallowChange = function() {
    $scope.dest.push({
      id: 1,
      name: 'Peter'
    });
  }

  $scope.rebuild = function() {
    $scope.dest = [{
      id: 1,
      name: 'Peter'
    }]
  }

  $scope.clear = function() {
    $scope.watchLog = [];
    $scope.watchCollectionLog = [];
    $scope.watchtrueLog = [];
  }
  $scope.clear();
}

<div ng-app>
  <div ng-controller='demoCtrl'>
    <h1>比較$watch()與$watchCollection()的不同</h1>
    <input type='button' value='屬性改變（深層）' ng-click='deepChange()'>
    <input type='button' value='屬性改變（淺層）' ng-click='shallowChange()'>
    <input type='button' value='重建物件' ng-click='rebuild()'>
    <input type='button' value='清除' ng-click='clear()'>
    <h2>$watch()</h2>
    <li ng-repeat='log in watchLog'>{{log.log}}</li>
    <h2>$watchCollection()</h2>
    <li ng-repeat='log in watchCollectionLog'>{{log.log}}</li>
    <h2>$watch(, true)</h2>
    <li ng-repeat='log in watchtrueLog'>{{log.log}}</li>
  </div>
</div>