Light types in Maya using Arnold
Point light - most sources of light in an environment are point lights. Such as lamps, streetlights, and overhead lighting.
Directional light - This is light for a very distant source, much like light from the sun. The light rays are parallel to one another.
Spot Light - Control the shape, and direction using a spot light. This is essentially a point light with an adjustable cone around it.
Area light - Can give a softer cast of light, but at a cost to rendering time. Looks like a soft box in the scene.