CLRMetaDiff (Common Language Runtime Metadata Difference) is a tool to compare the differences between versions of CLR assemblies.
The tool compares changes between the types and type members contained within two assemblies or two directories of assembilies with matching file names.
It was also made very quickly for a one time use and probably won't be updated...
CLRMetaDiff.exe [original-file-or-dir] [changed-file-or-dir]
Note: you can only compare files to other files or directories to other directories, not both!