Creating a third difference-only folder using rsync to compare 2 folders

[Eoin O'Sullivan]

I cannot find a clear answer to the following question ... 
I have 2 local websites on my LAN with 1,000+ files incl subdirectories
& 300Mb+ size.
I am using rsync to update 1 folder based on changes in the other folder
however I also need to compile a 2nd copy of ONLY the files that have
changed and put these in a 3rd folder so I can FTP them to a live
website (which doesn't support rsync). 

How can I do this with rsync?? Or is there another way, I am using OSX.

Folder A (contains website with some changes)
Folder B (contains older version of website)
Folder C (should contain only the files/folders that are different
between A & B)

How I think it should work ....

Compare Folder A to Folder B ... Any differences to be copied to Folder
C.
Then Update Folder B with changed files from Folder A (this is working
OK)

Any tips, solutions appreciated.

Thanks

Eoin

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