Here's why:

* Brightness is measured in luminosity: The sun is a massive star that emits an enormous amount of light and energy. Its luminosity is far, far greater than that of a lightning bolt.

* Distance matters: While a lightning bolt might appear extremely bright when viewed close up, the sun is much farther away. Even with its immense brightness, the sun's light is diluted by the vast distance it travels.

* Different types of light: Lightning produces a brief flash of white light, while the sun emits a wide spectrum of light, including infrared, visible, and ultraviolet.

Think of it this way: Imagine a tiny, powerful flashlight compared to a giant, distant beacon. The flashlight might seem bright up close, but the beacon's light will still be far stronger, even though it appears less intense due to its distance.