User menu tab content
I think you'd be better off creating 2 separate forms for each tab, but if you want one form to handle both you can use the function menu_get_item() to determine the menu path that routed to the form. 

  $menu_item = menu_get_item();
  if(isset($menu_item['path']) &amp;&amp; $menu_item['path'] == 'user/%/Privacy-Statement') {
    //@TODO: Add form elements specific to privacy tab
  }