RFA (Revit Family) files are used in Autodesk Revit, a popular building information modeling (BIM) software. RFA files contain 3D models, families, and other design elements. On the other hand, DWG (AutoCAD Drawing) files are used in Autodesk AutoCAD, a widely-used computer-aided design (CAD) software. DWG files contain 2D and 3D designs, including lines, arcs, and other geometric shapes.