WiMAX stands for Worldwide Interoperability for Microwave Access. In this paper, performance evaluation of WiMAX and LTE (Long term Evolution) is done on network simulator NS version 2.34. Both are subjected to Real life scenarios to see how different factors viz. distance, number of subscriber stations, different modulation schemes and packet size affect the performances of WiMax and LTE. Simulation is carried out for UDP protocol over fixed as well as mobile networks. Throughput, average delay and average jitter are used as performance metrics in this paper.