Light type :
Ambient: the light intensity is the same in all points and all directions.
Point: light from a point in all directions (same as having a bulb).
Directional: light from a single direction (same as having a very distant light source as the sun).
Spot: light from a point in a given direction and a limited field (aperture). The penumbra area allows to soft the transition between the lighted area and the obscure one.