The explanation for all types of refraction involves a change in

Direction

Explanation:

Refraction: It is a process in which when a light ray passes from one medium to another medium then the direction of light ray changes.

Refraction are of two types

Rare medium: The medium of low refractive index than the other medium in which refraction takes place  is called rare medium.

Denser medium: The medium of high refractive index than other medium in which refraction takes place is called denser medium.

Refraction from rare medium to denser medium: when a light passes from rare medium of low refractive index  to the denser medium of higher refractive index then the light ray bend towards the normal.

Refraction from denser  medium to rare medium: When a light ray passes from denser medium to rare medium then the light will be refracted away from from the normal.

Hence, the refraction involve a change in direction.