title: Rendering differences in Bootstrap 3 vs Bootstrap 4 Display Property classes
body: <p>I am interested to learn whether there are rendering differences between Bootstrap 3 and 4 Display Classes, given there is a 1-to-1 mapping between the class names and no perceivable other differences. So I am ignoring why this has been done.</p>
  
  <p>In Bootstrap 3 you could have a <a href="https://getbootstrap.com/docs/4.0/utilities/display/#hiding-elements" rel="nofollow noreferrer">Display Property</a> like this:</p>
  
  <pre><code>&lt;div class="hidden-xs"&gt;...&lt;/div&gt;
  </code></pre>
  
  <p>In Bootstrap 4 the equivalent is:</p>
  
  <pre><code>&lt;div class="d-none d-sm-block"&gt;...&lt;/div&gt;
  </code></pre>
  
  <p>As far as I can tell, the rendered output from these 2 things is identical. So ignoring "why" the names have been changed, <strong>is there any other difference between these two statements from a rendering perspective?</strong> Or, do they do identical things?</p>
  
  <p><a href="https://stackoverflow.com/questions/35351353/missing-visible-and-hidden-in-bootstrap-v4">Missing visible-** and hidden-** in Bootstrap v4</a> shows us that there is a 1-to-1 mapping between various Bootstrap 3 classes and the Bootstrap 4 equivalent.</p>
  
  <p>Are they identical in terms of rendering or <b>do the additional class names in Bootstrap 4 provide other functionality</b>?</p>
  
  <p>The linked post does not answer this question, because it says: 
  </p>
  
  <blockquote>
    <p>The <code>hidden-*</code> and <code>visible-*</code> classes no longer exist in Bootstrap 4. If you want to hide an element on specific tiers or breakpoints in Bootstrap 4, use the <code>d-*</code> display classes accordingly.</p>
  </blockquote>
  
  <p>It then goes on to show a 1-to-1 mapping for every Bootstrap 3 class name to the Bootstrap 4 equivalent. This does not confirm or deny whether there are <i>other differences</i> between what these display classes do in 4 vs 3. Therefore this is a legitimate question that needs a definitive answer.</p>
  
  <p>Please be aware:</p>
  
  <ol>
  <li>The proposed duplicate does not answer this question.</li>
  <li>Many people use Bootstrap 3 and 4 - or are migrating from one version to another. Knowing the answer to this is useful as it helps ensure they are not changing rendering behaviour inadvertently. </li>
  <li>The Bootstrap 3 (or 4) docs don't answer it.</li>
  </ol>