Lead Halide Perovskites (LHP) colloidal nanocrystals (NCs) easily self-assemble into ordered Superlattices (SLs) exhibiting uncommon collective emission properties (superfluorescence). LHP SLs also show atomic interference between NCs due to alignment of atomic planes, manifesting as multiple fringes of the 100 / 200 (cubic notation) X-ray peaks in 1D WAXS patterns. In our ongoing research on the topic, we investigate possible interplay between structural interference and collective emissive properties. Here, we intend to perform high-resolution in-situ and ex-situ combined 2D GIWAXS/specular diffraction experiments on fully inorganic / hybrid LHP NC SLs, aiming at: i) monitoring self-assembly from the early-stages taking place inside the colloidal suspension upon slow-solvent evaporation, to the final dried film, possibly exploring in-plane and out-of-plane atomic interference; ii) studying atomic interference in binary SLs grown ex-situ as sub-micrometer thick films.