Light Emitting Devices or Light Emitting Diodes (LEDs) (also called DEL in French, or « Diode électroluminescente ») are solid state components that produce brilliant light when an electric current is applied to a semiconductor chip. This process, electroluminescence, is much more efficient than incandescent light sources.
The energy efficiency quantifies the energy emitted by the source of light in relation to what it consumes. The relation is qualified as a percentage because both powers are referred to in wattage.
The luminous efficiency is the ratio of what the eye sees (lumens) to the light’s power consumption (watts). This relation is described in lumens per watt (lm/W).