Next generation QTAIM was used to explain the structural preferences and differences of a series phenolic esters and nitrogen analogues. The planarity of the nitrogen analogue structures was explained by a resistance to torsion of the N-linking bond. Conversely, a resistance to planarity of the O-linking bond in the phenolic esters explained the twisted geometries. Hydrogen bonding that linked the aromatic ring with the rest of the molecule was only found to be present for the nitrogen analogues. Confirmation of the findings was provided by a stress tensor analysis.