function views_ajax_form_wrapper($form_id, &$form_state)

• $form = drupal_build_form($form_id, $form_state);
• $output = drupal_render($form);

function drupal_build_form($form_id, &$form_state)

• $form = drupal_retrieve_form($form_id, $form_state);
• drupal_prepare_form($form_id, $form, $form_state);
• drupal_process_form($form_id, $form, $form_state);
• return $form;