Light-emitting diode (LED) and incandescent light bulbs produce light using different technologies. A traditional incandescent bulb produces light by passing electricity through a tungsten filament surrounded by inert gases to heat the filament to approximately 4,000 degrees Fahrenheit. An LED consists of two adjoined pieces of semiconductor material. Energizing an LED causes movement of electrons across the diode, which emits photons or light.
Incandescent bulbs are inexpensive and produce good light, but they don't last long. The high temperatures passing through the filament cause it to break down over time. In addition, they are inefficient; 90 percent of their energy escapes as heat. LED bulbs have long life spans, are efficient and produce little heat. However, they are expensive.
A power rating expressed in watts indicates the brightness of an incandescent light bulb. Bulbs with higher wattage ratings have larger filaments and produce more light. However, wattage actually indicates the amount of electricity the bulb needs to work; lumens measure light output. Because LED bulbs require less electricity to produce light, wattage ratings differ from those of incandescent bulbs. LED bulb manufacturers indicate the strength of the light that bulbs emit using lumens. The LED equivalent of a 40-watt incandescent bulb produces 250 lumens and the 100-watt equivalent produces 1,600 lumens.