Larger surface area. There's a balance of physics between the prop surface area, weight, spin speed, an material stresses. I like the carbon fiber for the weight and even distribution of acceleration stress. Also, the design pushes more air. However, because they push more air, they have greater resistance and move slower. The trade off ends up being a positive though. The increased thrust efficiency compensates for the slower movement so you get a net increase in flight time and control. You have more responsive controls because the amount of air displaced will be a larger volume, this fast reaction to user inputs.