do you mean directories or files?
does an update create new directories in the tarball? I would expect just updated files.
http://ftp.debian.org/debian/dists/Debian7.4/main/i18n/
has 03-May-2013 on most of the files, but not all.
and I would expect all the files here to be part of the next 7.5 (without knowing anything about how things are organized).
http://ftp.debian.org/debian/dists/wheezy/main/i18n/
Can I see that tarball somewhere?