title: Bootstrap: dropdown vs button dropdown
body: <p>In the Bootstrap documentation, there seems to be two different ways to create a dropdown:</p>
  
  <ul>
  <li><code>.dropdown</code></li>
  <li><code>.btn-group</code></li>
  </ul>
  
  <p>The <a href="http://getbootstrap.com/components/#dropdowns-example" rel="noreferrer">first</a> is as follows:</p>
  
  <pre><code>&lt;div class="dropdown"&gt;
    &lt;button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true"&gt;
      Dropdown
      &lt;span class="caret"&gt;&lt;/span&gt;
    &lt;/button&gt;
    &lt;ul class="dropdown-menu" aria-labelledby="dropdownMenu1"&gt;
      ...
    &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>The <a href="http://getbootstrap.com/components/#btn-dropdowns-single" rel="noreferrer">second</a> is as follows:</p>
  
  <pre><code>&lt;div class="btn-group"&gt;
    &lt;button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"&gt;
    Dropdown 
    &lt;span class="caret"&gt;&lt;/span&gt;
    &lt;/button&gt;
    &lt;ul class="dropdown-menu"&gt;
      ...
    &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Is one way preferred over the other?</p>