Refraction:
This is a phenomenon in which light changes its direction of travel when it strikes between the interface of the two different media.
Dispersion: Dispersion is splitting of light into its seven constituent colors i.e. violet, indigo, blue, green, yellow, orange and red.
The key difference between the two is that dispersion is referring to the frequency dependence (which is the ability to separate different colors of light) while refraction is referring to the bending of light in a material.