Design of lighting system:
Lighting provided from a source without reflection from other surfaces. In day lighting, this means that the light has travelled on a straight path from the sky (or the sun) to the point of interest. In electrical lighting it usually describes an installation of ceiling mounted or suspended luminaires with mostly downward light distribution characteristics.
Lighting provided by reflection usually from wall or ceiling surfaces. In day lighting, this means that the light coming from the sky or the sun is reflected on a surface of high reflectivity like a wall, a window sill or a special redirecting device. In electrical lighting the luminaries are suspended from the ceiling or wall mounted and distributes light mainly upwards so it gets reflected off the ceiling or the walls.