The confinement effects of electrons in ultrathin films and nanowires grown on metallic and semiconducting substrates investigated using band mapping of their electronic structures using angle-resolved photoemission spectroscopy is discussed here. It has been shown that finite electron reflectivity at the interface is sufficient to sustain the formation of quantum well states and weak quantum well resonance states even in closely matched metals. The expected parabolic dispersion of sp-derived quantum well states for free-standing layers undergoes deviations from parabolic behaviour and modifications due to the underlying substrate bands, suggesting the effects of strong hybridization between the quantum well states and the substrate bands. Electron confinement effects in low dimensions as observed from the dispersionless features in the band structures are also discussed.