It has been reported to be difficult to differentiate Lumbar Spinal Canal Stenosis (LSS) at the L4 level and Hip Osteoarthritis (HipOA) since Macnab reported that these diseases show very similar symptoms. Although the walking on these diseases have been analyzed separately, the comparison between them has not been done yet. In this paper, the walking on thirteen normal healthy persons, nine L4 patients and eighteen HipOA patients were analyzed for disease differentiation. The walking of the subject with LED markers was captured on the treadmill. The markers are attached on acrominon, spina iliaca anterior superior, head of fibulae, lateral malleolus and the fifth metatarsal head of the subject. Motion ranges of thigh angle (corresponding to hip angle), knee angle, upper body angle, and single stance ratio by the diseased leg were picked up as the important features for the differentiation. The motion ranges of the thigh angle and the single stance ratio on HipOA patients were smaller than those on normal healthy persons, as previously reported by other researchers. The motion range of thigh angle on HipOA patients was also smaller than that on L4 patients, and statistical significant difference between L4 and HipOA patients was obtained at the ten percent significant level. The motion ranges of knee angle became small in the order of normal healthy persons, L4 patients and HipOA patients while that of upper body angle became large in the order of L4 patients, normal healthy persons and HipOA patients. With respect to the angles of knee and upper body, statistical significant difference between L4 and HipOA patients was obtained at the five percent significant level. In conclusion, the above four feature factors, especially the motion ranges of upper body angle and knee angle are effective to differentiate the HipOA and L4 patients.