Actually the yarn cross-section and the cotton fibre cross-section are neither in the form of a circular nor hexagonal. The yarn cross-section tends to concentrate the structure packed form of irregularly polygonal with elliptical form appearance along the length of the yarn, due to tension, twist and yarn count. In the earlier research works (parts 1, 2 and 3) we approached equations to calculate the mayor and minor yarn diameters (D, d) of the RS, OE, and VS spun yarns as elliptical model. In this research work a study of the yarn cross-sectional properties (minor diameter d, mayor diameter D, Eccentricity e, profile cross-section area Ap, real elliptical area Ar, profile circumference Up, real elliptical circumference Ur, the packing density Pd and spun deformation factor Df) as a Comparison between the Ring Spun yarns RS, Open End yarns and Vortex Spun yarns VS. As results the packing density of the VS spun yarns was higher than the OE cotton yarns and less than the RS cotton yarns, by other mean found that the RS cotton yarns more compacted than the VS (6%) and OE cotton yarns (16%). The minor OE yarn diameters (d) increase 14% and 8% than the RS and VS minor diameters respectively while the mayor diameter (D) increase 8% and 5% only respectively, in the same time the minor (d) and mayor (D) VS yarn diameters increase 6% and 3% only respectively than the RS diameters (d, D). The deformation factor of the open end yarns (Df(OE)) was more than the deformation factor of the ring spun yarns (Df(RS)) and vortex spun yarns (Df(vs))