The comparison of bimodal pore structures between silica gels prepared from silicon alkoxide and from water glass was performed based on the results of phase separation tendency, mesopore formation, and atomic scale observation using Si-29 NMR. Macropore structure could be controlled for both the raw material systems by inducing phase separation. Although the gelation in the water glass system is much faster than that in the silicon alkoxide system, there is little difference in the atomic scale structure, mesopore evolution during processing, and phase separation tendency. The results suggest that the obtained bimodal porous silica from water glass is essentially the same as that from silicon alkoxide. Because of the low cost of water glass, water- glass- derived bimodal porous silica is applicable to industrial use.