http://russian.stackexchange.com/questions/1211/whats-the-difference-between-%D0%BB%D0%B5%D0%B6%D0%B8%D1%82-%D0%BD%D0%B0-%D1%81%D1%82%D0%BE%D0%BB%D0%B5-and-%D1%81%D1%82%D0%BE%D0%B8%D1%82-%D0%BD%D0%B0-%D1%81%D1%82%D0%BE%D0%BB%D0%B5