title: $variables Vs. $vars
body: <p>What is the difference between</p>
  
  <pre><code>function mythemes_preprocess_node(&amp;$variables) { ... }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>function mythemes_preprocess_node(&amp;$vars) { ... }
  </code></pre>
  
  <p>in drupal 7.
  and what is the difference between preprocess and process functions.
  thanks.</p>