Regular reflection occurs when light waves bounce off a smooth and flat surface at the same angle at which they hit the surface. This type of reflection creates a sharp image because the light waves remain parallel to each other after reflection, allowing them to converge at a single point and form a clear and focused image. In contrast, irregular or diffuse reflection occurs when light waves bounce off a rough or uneven surface in various directions, causing the light to scatter and not converge at a single point. This results in a blurry or distorted image.