Drawing (DWG) is a format for storing two and three dimensional design data and metadata.
It is the native format for several CAD packages including AutoCAD, Intellicad and its variants,
Caddie and DWG is supported non-natively by many other CAD applications.

Drawing Exchange Format (DXF) is a 3D graphic image format that's originally created by
AutoDesk in order to store 3D scenes and models. Popular 3D programs like 3D Studio Max
can export geometry using the DXF format for easy importation into UnrealED.

Design Web Format (DWF) is a highly compressed file format established for viewing and
printing Auto CAD drawings and other 2D vector files and sending them over the Internet.
This lightweight AutoCAD format is a fast, efficient way to distribute design data. What
you see is exactly what the is intended, because the information cannot be changed.