C9 and C7 lights are traditional LED Christmas light shapes; however, there are some differences between the two. The main difference between the C7 and C9 LED Christmas lights is their bulb size. Generally, C7 LED light bulbs are 2 inches high while C9 LED light bulbs are 3 inches high. Despite their difference in size, both the C7 and C9 LED light uses only 0.15 watts of energy. These lights are typically used for outdoor lighting displays since their larger size bulb can be seen from farther away. They commonly adorn houses, stores, restaurants, trees, bushes, decks, etc.