1) Great boxers over great punchers
2) As you can see when they pose together, Mayweather is the naturally larger man. He started as a junior lightweight and grew into a welterweight. Pacquiao started a sa flyweight and built himself into a welterweight. There's a difference.
3) Pacquiao is a year young but is the older fighter, having taken punches to deliver them. Mayweather makes his man miss and counters. Manny gained fans as an action fighter but he's been through to many wars. Mayweather ahs avoided the wars.
4) Manny's been beaten five times and drawn twice. Marquez, who Mayweather easily beat, had one draw and almost killed Manny when they last fought. nobody's beaten Mayweather.