There are a few ways to tell if a light bulb is LED or incandescent. One way is to look at the shape of the bulb. LED bulbs are usually more tubular in shape, while incandescent bulbs are more round. Another way is to look at the color of the light. LED bulbs emit a more blue-ish light, while incandescent bulbs emit a more yellow-ish light. Finally, you can look at the wattage of the bulb. LED bulbs typically use less wattage than incandescent bulbs.