rpmdiff is a utility to create a binary patch from one version of an rpm to another. This binary patch can then be distributed to end-users of a distribution who have installed the first version of the rpm and they will be upgraded to the second version.
ebsdiff creates a binary patch file using the bsdiff format. The enhancements to bsdiff are that it stores an MD5 hash of the original file (preventing accidental patching of the wrong file) and can limit the memory it uses while creating the patch file.