Single-slit diffraction results in a central bright fringe, surrounded by alternating dark and bright fringes, while double-slit interference produces evenly spaced bright fringes. For a more detailed exploration, refer to the section on diffraction patterns.

In single-slit diffraction, light waves passing through a narrow slit spread out and interfere with one another, forming a pattern of bright and dark fringes on a screen. The central fringe is the brightest and widest, with the intensity of light decreasing as one moves away from the center. This pattern arises from the constructive and destructive interference of the light waves. Constructive interference occurs when the waves are in phase, resulting in a bright fringe, while destructive interference happens when the waves are out of phase, leading to a dark fringe. The width of the fringes in single-slit diffraction is influenced by both the width of the slit and the wavelength of the light. A deeper understanding of these concepts can further clarify how these fringe patterns develop.

In contrast, double-slit interference involves light passing through two closely spaced slits. The light waves emanating from each slit spread out and overlap, generating an interference pattern characterized by evenly spaced bright fringes on a screen. Similar to single-slit diffraction, this pattern also results from constructive and destructive interference. However, in double-slit interference, the bright fringes are equally bright and uniformly spaced, which distinguishes it from the single-slit pattern. The spacing of the fringes in double-slit interference depends on the distance between the slits and the wavelength of the light. For a comprehensive understanding, please consult the relevant section.

In summary, single-slit diffraction causes light to spread out, resulting in a pattern with a prominent central fringe and progressively less intense fringes as one moves away from the center, due to the interference of light waves. Conversely, double-slit interference generates a pattern of bright fringes that are uniformly bright and spaced, resulting from the overlap of light waves from two slits. The two patterns differ in terms of brightness, spacing, and the mechanisms by which they are created.