In embedded almost everybody uses efficient binary delta diffs and patching for DFOTA (delta firmware over the air update). Jojodiff exists as GPL and MIT variants.

http://jojodiff.sourceforge.net/

https://github.com/janjongboom/janpatch

Rsync is also very popular, even if not that efficient. xdelta, bsdiff, BDelta, bdiff are all crap.