What is the difference between an LED and an incandescent light bulb?
An incandescent light bulb produces light by passing electricity through a filament, heating it to the point that it glows and generates light. These light bulbs have a balanced light spectrum, with a high amount of red, which creates warm cozy lighting without unpleasant or harmful effects such as flickering. Such bulbs are not energy efficient since most of the energy generates heat, not light.
LED bulbs emit light as a result of current going through a crystalline semiconductor diode. White light cannot be generated, it requires a mix of light, therefore in many LEDs phosphor material is illuminated by blue light, which in turn emits yellow light with a fairly broad spectral power distribution. The impact of these lights is controversial and applies to warm white LED bulbs as well. Blinding and flickering are further problems; LEDs are presently the most energy efficient bulbs in use.