An FBX file is a format used to exchange 3D geometry and animation data. The FBX files are used in film, game and augmented reality and virtual reality (AR/VR) development. Also, in order to open, edit, and export FBX files to high-fidelity 2D and 3D files, we need some third-party software like Autodesk FBX Review,etc. Whereas, OBJ is a much simpler format that only keeps geometry (vertex, normals, etc) and is often for raw polygon data, some simple materials.