Pheasant\Schema::diff PHP Method

    public function diff($o1, $o2)
    {
        $diff = array();
        foreach ($this->_props as $key => $prop) {
            if (!$prop->type->equals($o1->get($key), $o2->get($key))) {
                $diff[] = $key;
            }
        }
        return $diff;
    }