FBX (Filmbox) is a proprietary file format (*fbx) developed by Kaydara and owned by Autodesk since 2006. It is used to provide interoperability between digital content creation applications. The format saw wider support from other 3D software packages such as Cinema 4D, SoftImage 3D, PowerAnimator, LightWave 3D and 3D Studio MAX. Today, FBX is also widely adopted among VR applications, which are typically built on top of major game engines.
AutoCAD DXF (Drawing Interchange Format, or Drawing Exchange formal) is a CAD file format created by Autodesk for AutoCAD more compatible with other programs.
DXF was initially intended to represent exact copy of the data in the AutoCAD native format DWG (Drawing).
It can’t hurt if we mention that DXF coordinates come always without dimensions so the user needs to know the drawing unit or has to extract it from the textual comments in the sheets.