title: What's the difference between array_merge and array + array?
body: <p>A fairly simple question. What's the difference between:</p>
  
  <pre><code>$merged = array_merge($array1, $array2);
  </code></pre>
  
  <p>and</p>
  
  <pre><code>$merged = $array1 + $array2;
  </code></pre>
  
  <p>?</p>