Various sectors are likely to carry a set of emerging applications while targeting a reliable communication with low latency transmission. To address this issue, upon a spectrally-efficient transmission, this paper investigates the performance of a one full-dulpex (FD) relay system, and considers for that purpose, two basic relaying schemes, namely the symbol-by-symbol transmission, i.e., amplify-and-forward (AF) and the block-by-block transmission, i.e., selective decode-and-forward (SDF). The conducted analysis presents an exhaustive comparison, covering both schemes, over two different transmission modes, i.e., the non combining mode where the best link, direct or relay link is decoded and the signals combining mode, where direct and relay links are combined at the receiver side. While targeting latency purpose as a necessity, simulations show a refined results of performed comparisons, and reveal that AF relaying scheme is more adapted to combining mode, whereas the SDF relaying scheme is more suitable for non combining mode.