With injected hair all the cuticles are going in the same direction just like naturally growing hair. With a knotted unit the cuticles go in one direction on the end of the hair shaft going into the base and then the opposite direction coming coming out of the base. The knotted hair has more 'poof' because of this. Depending on the hair style, the 'poof' may work in favor of the style---it all depends on the look you're trying to achieve.