It is not so much about the material used in the bow riser (handle), but about the material used in the limbs. Limbs can be made of fibreglass, laminated wood, carbon fibre or a composite of these materials. While limbs made from each material may have a rating of 34lb at 28” draw length (i.e. the same force exerted on your fingers at full draw), it is how the material stores and returns this energy that is important (energy profile). Carbon limbs are more energy efficient and impart greater speed to the arrow (snaps back quicker from full draw) than wood limbs, and does so consistently over a range of environmental conditions. Carbon limbs are very expensive.