This is a diff tool to compare the CLI metadata in .NET assemblies or WinMD files.
LibCheck (Free) https://www.microsoft.com/en-us/download/details.aspx?id=11287
Framework Design Studio (Free) http://archive.msdn.microsoft.com/fds
BitDiffer (Commercial) http://www.bitwidgets.com/
NDepend (Commercial) http://www.ndepend.com/