title: bootstrap inlining with d-inline-block
body: <p>I am improving my bootstrap skills, i wanna know why in one place for inlining one work and in one place another, here : d-inline-block and this form-inline, what it difference between this two and why for example using 'form-inline' in 'd-inline-block' place wont work ? both has form classes ?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
    &lt;meta charset="utf-8"&gt;
    &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
    &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css"&gt;
    &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"&gt;&lt;/script&gt;
    &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"&gt;&lt;/script&gt;
    &lt;script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"&gt;&lt;/script&gt;
    &lt;link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.0.13/css/all.css" integrity="sha384-DNOHZ68U8hZfKXOrtjWvjxusGo9WQnrNx2sqG0tfsghAvtVlRW3tvkXWZh58N9jp" crossorigin="anonymous"&gt;
    &lt;style&gt;
    body{
    padding:0px;
    margin:0px;}
  
  
    
    &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
      &lt;div class="form-group form-inline pt-4"&gt;
        &lt;div class="col-sm-10"&gt;          
          &lt;div class="fas fa-lock"&gt;&lt;/div&gt;    &lt;input type="password" class="form-control" id="pwd" placeholder=" password" name="pwd"&gt;
        &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class=" "&gt;        
        &lt;div class="col-sm-offset-2 col-sm-10"&gt;
          &lt;div class="checkbox"&gt;
          &lt;/div&gt;
        &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class="form-group d-inline-block"&gt;          
          &lt;button type="submit" class="btn btn-success ml-3"&gt;Login&lt;/button&gt;
        &lt;/div&gt;
          &lt;div class="form-group d-inline-block"&gt;       
          &lt;button type="submit" class="btn btn-primary"&gt;Login with facebook&lt;/button&gt;
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/form&gt;
  &lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>