The image formed by a mirror is virtual because it is formed by the reflection of light rays. These light rays do not actually converge at a point to form the image, but instead appear to diverge from a point behind the mirror. This means that the image cannot be projected onto a screen and can only be seen when looking into the mirror.

On the other hand, the image formed by a pinhole camera is real because it is formed by the actual convergence of light rays. In a pinhole camera, light passes through a small hole and forms an inverted image on the opposite side of the camera. This image can be projected onto a screen or captured on film, making it a real image.