Files with DWG extension represent proprietary binary files used for containing 2D and 3D design data. Like DXF, which are ASCII files, DWG represents the binary file format for CAD (Computer Aided Design) drawings. It contains a vector image and metadata for the representation of the contents of CAD files.
A file with .emz extension is a compressed container of Enhanced Metafile (.emf file). It follows GZIP compression algorithm and takes less storage space due to compression. The small file size makes it more easy to transfer EMZ files over the network.
You can also convert DWG into many other file formats. Please see the complete list below.