pkgdiff (visualize changes in tgz/rpm/deb/etc archives)

Package Changes Analyzer (pkgdiff) - a tool for visualizing changes in
Linux software packages (RPM, DEB, TAR.GZ, etc). The tool is intended
for Linux maintainers who are interested in ensuring compatibility
of old and new versions of packages. It's useful for both source and
binary packages.

The tool can compare directories as well (with the help of the -d
option).

Sample report:
https://abi-laboratory.pro/tracker/package_diff/libssh/0.6.5/0.7.0/report.html

NOTE: Slackware 15.0's pkgtools added a pkgdiff command. It's
installed to /sbin, whereas this pkgdiff goes in /usr/bin, so there's
not a conflict. Non-root users generally don't have /sbin in $PATH,
so they'll get this pkgdiff by default. Root's $PATH includes
/sbin before /usr/bin by default, so root will get the Slackware
pkgdiff. Either way, you can always run the command with the full path
to select which pkgdiff you want.