How to compare DLL files

At the end of our Sw production line we would like to know which changes made it into the built .dll files. For that we would like to compare the .dll files generated with the .dll files of the previous version of the product. A simple compare doesn’t do because, due to the automatic generation each object in the .dll does have a new timestamp, and thus appears different. I am looking for a way to just compare the code! Any suggestions?