A set of optical sheets may perform at least one of diffusion, refraction, and condensation of light. The set of optical sheets may include a first optical sheet that includes a first base film and a first distinction unit disposed outside the first base film. The set of optical sheets may further include a second optical sheet that includes a second base film and a second distinction unit disposed outside the second base film. The second distinction unit may be spaced from the first distinction unit in a plan view of the set of optical sheets if the second base film complete overlaps the first base film.