They aren't related. They appear in SUSY Lagrangian as $L=\int\mathrm{d}^4 \theta K(\Phi, \overline{\Phi})+\left(\int\mathrm{d}^2 \theta W(\Phi)+c.c.\right)$,

here $K$ is a real-valued function of a chiral field $\Phi$ and its conjugate $\overline{\Phi}$, named Kahler potential, while $W$ is an analytic function of $\Phi$, named superpotential.

Being rewritten in the component fields, $K$ contains kinetic terms of these fields and certain interactions required by supersymmetry, while $W$ contains potential (and mass) terms plus, again, interactions dictated by supersymmetry.