file diff using rsync?

[Desmond Chan]

Hi all,
  I am new to rsync and would like to do the followings:
1. I would like to find out how to use rsync to get the difference between 
2 files.  I need to record the difference (insertion and deletion) between 
2 versions and I thought that rsync would be able to do so.  Can you tell 
me how to use rsync to do it?

2. I am trying to read the rsync code to find out how it computes the file 
diff and applies the diff to the file to be sync'ed.  Can you tell me which 
source files are relevant?

Thank you very much,

Desmond