$$\begin{gathered} Since thickness is same so force per unit length should be same \\ Force per unit length = F/2\pi R \\ Charge density in the sphere is proportional to E \\ so F \alpha qE \alpha \sigma AE \alpha E^2{R}^2 \\ Thus force per unit length \alpha E^2{R}^2/2\pi R \alpha E^{2}R \\ Now compare the two cases \end{gathered}$$