Epitaxial WS2 films have been grown on MoTe2 (0001) van der Waals faces using W(CO)6 and SnS2 as precursors. Despite a lattice mismatch of 10.3 % the film shows high crystalline quality. The interface is atomically abrupt and shows no interface dangling bonds as deduced from photoemission results (XPS, UPS). The growing overlayer nucleates on the flat (0001) terraces and not on steps as suggested from STM-measurements. For thin epilayers Moiré superstructures in LEED have been measured for the first time in semiconductor heteroepitaxy. From the intensity variation of the LEED spots with energy a corrugation of the overlayer film can be deduced. Based on these results a mechanism of van der Waals epitaxy is suggested.