With the all-up, if both horses win, you would spend $5 and get back $125. (5x5x5) With the other method, if both horses win, you would spend $10 and get back $50. (5x5 + 5x5) With the All-up though, both horses MUST win for you to win your bet, whereas betting the other way, only one of them needs to win for you to get something back.