There are basically two types of 'recurve' limbs. Dynamic, or working tips, and static tips. With working tip curves, the recurved hook opens up or unfolds during the latter part of the draw cycle. The profile of the hooks from unbraced to braced to full draw will change, sometimes dramatically. While a static tip hook does not open up during the draw cycle. The three above mentioned profiles will be identical or close to it. Both designs have their benefits, but generally speaking, a static tip will shoot quieter. Do a quick search here, and you'll find tons of info on static tips.