The term DECORATIVE LIGHTING covers all the traditional kinds of light fitting (floor lights, pendants, chandeliers, etc) and differentiates them from technical or architectural lighting (e.g. downlighters). The basis for the difference is that the decorative light fitting can be seen. And if it can be seen, it matters what it looks like. For example:
Melogranoblu 3 x Calaf (small)
Whereas, technical lights can be hidden in the wall, floor or ceiling, so you are not meant to see them at all. Tekna's Flat is a brilliantly executed downlighter: the lamp is almost invisible (because it is recessed up into the ceiling), and the structure manages to be almost invisible also. Plus, the beam spread is so good that there need be no light pool beneath it:
Another way of putting it is that, for technical lights, what is important is the lamp, whereas for decorative lighting, the emphasis is on what the luminaire looks like.
This must not be taken too far, however! Every light fitting will cast light but in different ways. Knowing in what way is essential to the specifying decision. As Ingo Maurer has said: "People buy for the shape [i.e. what the luminaire looks like] , but the quality [i.e. how it performs as a light-producing object] is more important - that it doesn't give you glare, that it makes you feel comfortable. You cannot buy a lamp for its shape."
There are lights that just glow, that look wonderful in a semi-formal setting:
Ombre Portée's Phebus at Rochefort-en-Yvelines Gold Club
Ombre PortéeCrop Circle
Ombre Portée's Crop Circle at Hôtel le Cardinal, Paris
At the opposite extreme there are task lights, whose main function is to put light where it is required. But they can still be seen -- what they look like (and, more broadly, what they are: who designed them, who made them, in what materials, etc.) is still important. The two most common types of tasklight are desk lights: