Comparative analysis of the electronic structure of thermally oxidized surfaces of silicon and silicon carbide indicates that in both cases the fundamental (bulk-band-related) spectrum of electron states is established within less than 1 nm distance from the interface plane. The latter suggests an abrupt transition from semiconductor to insulator. However, a large density of interface traps is observed in the oxidized SiC, which are mostly related to the clustering of elemental carbon during oxide growth and to the presence of defects in the near-interfacial oxides. Recent advancements in reducing the adverse effect of these traps suggest that the SiC oxidation technology has not reached its limits yet and fabrication of functional SiC/oxide interfaces is possible.