DWG Diff is a simple tool that displays the differences (and commonalities) between two drawings.

DWG Diff Features:
1. Compares all drawing entities in the selected drawing space (Model,Layout)
2. Compares all other drawing structures such as: Layers, Blocks, Text Styles, Layouts, etc.
3. Compare dwg drawings from R12 to 2007.
4. Creates three separate views outputs (A not B, B not A, and Common).
5. Comparative output can be saved as dwg, dxf, pdf.

The license of this software is Freeware, you can free download and free use this cad software.