Direct comparison of SnPc growth on a metal and a nearly insulating surface was achieved by adsorption of SnPc on Au(111) partially covered with NaCl. While on Au(111), SnPc lies flat and grows in a Stranski-Krastanov mode; on NaCl, Volmer-Weber growth of three-dimensional molecular nanocrystals occurs. On NaCl, intermolecular interactions dominate over the molecule-NaCl coupling and result in a tilted adsorption configuration.