UMTS/WCDMDA which is a third generation wireless mobile cellular technology has been adopted in most parts of the world and now undergoing a phase of evolution and will soon be emerge as LTE. On the other hand, WiMAX which is also some times called as fourth generation mobile broadband technology is likely to be accepted in many places. With higher data rates for transmission, adaptive modulation and coding, OFDMA based physical layer and a very flexible architecture, WiMAX appears to be suppressing UMTS soon. However, the Long Term Evolution (LTE) of 3G or UMTS is likely to compete the WiMAX both technically and economically. This research provides a comparative interpretation of architecture, salient features, robustness, physical layer, mobility, capacity and coverage aspects of the both UMTS/WCDMA and WiMAX broadband technologies. It also explains the error probabilities in transmission for modulation techniques employed in both technologies. This research helps developing a better understanding for operators and users to make a choice in preferring any of the technologies regarding different features.