Tool to compare .dlls and disassemble the differences?

Does anyone know a decent tool that will compare two different versions of the same dll and extract the differences?

thanks

From stackoverflow

• Why not disassemble first and then compare?

  Sandor Davidhazi : Exported with Reflector, then compared the directories with Beyond Compare. Just great! :)

• Reflector has a Diff tool.

  flesh : good stuff, thanks

  mkmurray : Does this still work with latest Reflector version? Mine just crashed doing a diff.

• Check http://www.red-gate.com/products/reflector/