if (isset($form['product_id']['#options'])) {
  $options = array_keys($form['product_id']['#options']);
  $products = commerce_product_load_multiple($options);
  foreach ($options as $key) {
    $form['product_id']['#options'][$key] = $terms_name[$products[$key]->field_product_type['und'][0]['tid']];
  }
  $form['product_id']['#title'] = 'DESIRED_LABEL';  // label for select box on product page
}