outer and inner diameters

"Kickpoint" is actually a passe term these days. Kickpoint is an old term in shaft design that was used to try to describe how the shaft's overall stiffness or flexibility was distributed over the entire length of the shaft.
Different bend profile designs of the same letter flex (i.e., R-flex) exist to help better match the bending feel and the trajectory the shaft offers the shot to the golfer's swing motions of transition, tempo and release.
By varying the outer and inner diameters of the shaft, along with the wall thickness in-between at any point along the shaft, it is possible to make shafts of the same overall stiffness but which differ in where they are more or less stiff. One shaft can be an R-flex but be more flexible in the tip end of the shaft, while another R-flex shaft can be made to be more tip-stiff. Same thing with the grip end of the shaft as well as the center section area of shafts.For example, it is possible to make two shafts of the same letter flex - such as an R-flex - that are different in their bend profile design.