The adsorption structures of oxygen and sulfur are compared for both ordered and disordered phases as determined by means of LEED and DLEED, respectively. Emphasis is on the comparison of the different chemical species as well as on the coverage dependence in each case. In the ordered phases both oxygen and sulfur adsorb in fourfold symmetric hollow sites, whereby in the disordered phases, i.e., for low coverages, mixtures with off-center sites seem to exist. The adsorption heights are coverage dependent obviously due to adatom-adatom interactions. Both species induce a substantial expansion of the first substrate layer distance which is larger for oxygen than for sulfur but increases linearly with coverage in both cases. Also, there is an adsorbate-induced buckling in the second substrate layer which is weakened with increasing coverage.