In this study, we compared the motion performance of a floating offshore wind turbine using South Korea's East Sea environmental conditions. Numerical simulation was performed using FAST v8 developed by the National Renewable Energy Laboratory (NREL), and the wind turbine model used for numerical analysis was referenced from the NREL 5MW Definition. The comparison was carried out for two types of floats, an OC3-spar and OC4 semi-submersible, composed of the same tower, nacelle, blade, and controller. The comparison was made in Korea's East Sea environmental conditions, located 50 km away from Ulsan Port with a water depth of 150 m. The length and characteristics of the mooring line were adjusted for each depth by the OC3-spar and OC4 semi-submersible. The environmental data were obtained from the Meteorological Administration's measured data and NASA's reanalysis data, MERRA-2. Design load cases were selected by referring to IEC 61400-3. The results were compared with the maximum moment at blade root and tower base. Also, the six-degree-of-freedom motion and three mooring line tension were compared. From the comparison results, the characteristics of each platform were confirmed.