public static function unitsAreDifferent($first, $second)
    {
        return
            (preg_match(UnitResolver::SI_PATTERN, $first) && preg_match(UnitResolver::IEC_PATTERN, $second)) ||
            (preg_match(UnitResolver::IEC_PATTERN, $first) && preg_match(UnitResolver::SI_PATTERN, $second));
    }