how to compare 2 .exe line by line?

Hi, i am curious on how to automaticly compare two .exe or .dll files line by line.
Was thinking of like comparing one original .exe version and one cracked .exe and then compare those two to see the difference in code they have changed. to see how they cracked it.
i dont mean the ascii code now as this could be seen and compared with ultraedit,
i mean the code you can see in ollydbg in cpu main thread window.

thnx in advance
/JayJay