Convenient way of maintaining differential backup of a large file
The only product that I know of that can handle binary files is an open source product called xdelta.

I have used it on Linux and it has worked really well.  However, there is a caveat and a big one - you must compile the application.  This means you are going to have to become familiar with compiling files on OS X.  This requires downloading the XCode development environment and issuing the make command.

I haven't done this on my personal mac as I keep my "dev" and "production" systems separate.  At the moment, I don't have a "dev" OS X box. I personally don't recommend installing development tools on production machines, but to each their own.  So....if you would like to install make on a Mac, refer to this article:
Installing "make" on a Mac

Some alternatives - check out this Wikipedia page for a list of alternatives based on rsync (built into OS X).  Your mileage may vary