ediff-directories

ediff-directories is an interactive autoloaded compiled Lisp function in `ediff.el'.

It is bound to <menu-bar> <tools> <compare> <ediff-directories>.

(ediff-directories DIR1 DIR2 REGEXP)

Run Ediff on a pair of directories, DIR1 and DIR2, comparing files that have
the same name in both. The third argument, REGEXP, is nil or a regular
expression; only file names that match the regexp are considered.