This brief article describes some features of nanocomposite photoactive materials and photoactive heterostructured materials that involve, respectively, materials doped with atoms, clusters, or quantum dots versus a combination of two or more narrow bandgap semiconductors that can absorb a significant quantity of solar light for the photochemical conversion of solar energy to solar fuels. Also discussed are the associated kinetic and thermodynamic factors that impact the relevant redox reactions. The principal difference between composite and heterostructured materials is the discrete versus the delocalized character, respectively, of the electronic interaction(s) between the components constituting the materials.