We have tried to compare two different IDSs which are widespread over the network administrator, Snort and Suricata, in functional and performance aspects. Specifically, we focused on analyzing upon what functions for detecting threat were added newly and what Multi-Threading introduced newly for Suricata has influenced in a performance aspect. As a result, we could discover that there are some features in Suricata which has never existed in Snort such as Protocol Identification, HTTP Normalizer & Parser, and File Identification. Also, It was proved that the gap of PPS (Packets Per Second) becomes wider, as the number of CPU Cores which are working increase. Therefore, we could conclude that Suricata can be an efficient alternative for Snort considering the result that Suricata is more effective quantitatively as well as qualitatively.