Point light or positional light: This type of light comes from a fixed position in the 3D space. The position of light and vertices of the object on which it falls is used to calculate the direction of the light. Point light emits light in all directions. Each vertex can have different directions of light, depending on its position from the light source, as shown in the following image.

Directional light: This type of light is a special case of the point light. Here, the direction of the light falling on the object is considered as nonvarying. This means that the direction of all the light rays are parallel. In directional light, the light source is considered infinitely far from the model, on which it's supposed to fall. Sometimes, it's better to assume the light direction to be parallel during the 3D scene rendering process. This...