Help?? Shoe sizes

Ladies I am getting my mom new Nikes for her Birthday. She wears a 10 in women, The pair of Nike shox I found are men's, They're her favorite color and I know she will love them. I googled what size she would wear in mens and it said 8, and I know that can't be right because my brother wears an 8 in men's and he tried her shoes on and they're alot bigger than his shoes. Anyone might know what size to order? These shoes are not cheap and I don't want to take her to get them either, The ones I like are only in stock online. Advice?