getting "diff" of directory trees

[N.J. Thomas]

Given two directories "foo" and "fooprime", can I have rsync make a file
or directory "d", that contains the differences between these two
directories such that I can take d and apply it to foo to get fooprime,
or take fooprime and reverse-apply d to it to get foo?

I'm not sure that the --backup and --backup-dir options to rsync will
give me exactly what I want.

thanks,
Thomas

-- 
N.J. Thomas
njt at ayvali.org
Etiamsi occiderit me, in ipso sperabo