Non Orthogonal Multiple Access (NOMA) is a candidate multiple access scheme for 5G. The fact that NOMA allows multiple users to transmit and receive simultaneously using the same frequency may appear intriguing. The two key operations that make NOMA possible are superposition coding which must be done at the transmitter side and successive interference cancellation (also known as SIC) at the receiver side. In this study, some comparisons has been done to examine NOMA and OMA in bit error rate, capacity, energy efficiency, number of users, and receiver complexity the results show that NOMA is the best especially in capacity and energy efficiency, although his sensitivity to bit error rate.