Internal surface structure of 13 samples of base-catalyzed silica aerogels synthesized using different reactant concentrations (TEOS, H2O) was investigated by means of small-angle X-ray scattering (SAXS) and Ng adsorption. Both SAXS and Frankel-Halsey-Hill plots of adsorption isotherms, interpreted in terms of equations of Pfeifer and co-workers, consistently show fractally rough surface structure for aerogels obtained from the low water content procedure and fractally smooth surface of those obtained with overstoichiometric water content.