In heterobilayers consisting of different transition-metal dichalcogenide (TMDC) monolayers, optically excited electron–hole pairs can be spatially separated into the adjacent layers due to a type-II band alignment. However, they remain Coulomb correlated and form interlayer excitons (ILEs), which recombine radiatively. While these ILEs are observed in several TMDC material combinations, their characters and properties depend on the specific system. Herein, some of these peculiarities are demonstrated by comparing studies performed on two different heterobilayer combinations: MoS₂–WSe₂ and MoSe₂–WSe₂.