title: What is the difference between cat_id and term_id?
body: <p>I'm building my own nav menu using custom taxonomies and the get_categories() method and I notice when I'm trying to pull my link for the category I can choose between <code>cat_id</code> and <code>term_id</code>.  Is there a difference between the two? Which one should I be using?</p>
  
  <p>Here's an example of my code using the <code>term_id</code></p>
  
  <pre><code>foreach ($subcategories as $subcategory) {
      $output .= '&lt;li&gt;&lt;a href="'. get_category_link($subcategory-&gt;term_id) .'"&gt;' . $subcategory-&gt;name . "&lt;/a&gt;&lt;/li&gt;\n";
  }
  </code></pre>