title: What's the difference between Bootstrap Spans & Columns
body: <p>I working with bootstrap but trying to understand the difference between Spans and columns, </p>
  
  <p>example </p>
  
  <pre><code>&lt;div class="span4"&gt;...&lt;/div&gt;
  or 
  &lt;div class="col-md-4"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>What's the difference between them or do they do same thing?</p>