title: Laravel Collection Diff not returning difference between two collection
body: <p>I am trying to get difference between two collection with diff function of laravel,but do not know why it always return 0 difference items, although $col1 contains 6 items and $col2 contain 5 items,
  My code:</p>
  
  <pre><code>$col1=collect([$data['result']-&gt;items()]);
  $col2=collect([$data['erp_data']]);
  $diff=$col1-&gt;diff($col2);
  dd($col1,$col2,$diff);
  </code></pre>
  
  <p>and it returns</p>
  
  <p><a href="https://i.stack.imgur.com/K2zVF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/K2zVF.png" alt="result"></a></p>
  
  <p>Help needed,thanks.</p>