A new classification scheme for epitaxial growth is proposed which incorporates the new epitaxy type Coincidence-III. The fundamental difference between organic-organic-heteroepitaxy and organic-inorganic heteroepitaxy is that in the former case the substrate unit cell might exhibit multiple locally favorable adsorption positions for a single overlayer molecule. An analysis of the respective Fourier series representation of the V_inter potential reveals why coincident-III overlayer domain orientations can be energetically favorable alignments: Depending on the energetic\ntopology within a substrate unit cell, resonances in the lock-in term can occur for higher order terms of the Fourier series which might then dominate the V_inter potential.