• dh_install, will fall back to looking for files in debian/tmp if it doesn't find them in the current directory (or wherever you tell it look using --sourcedir). This allows dh_install to interoperate with dh_auto_install, which installs to debian/tmp, without needing any special parameters.
• dh_clean will read debian/clean and delete files listed there.
• dh_clean will delete toplevel *-stamp files.
• dh_installchangelogs will guess at what file is the upstream changelog if none is specified.

• Commands that generate maintainer script fragments will order the fragments in reverse order for the prerm and postrm scripts.
• dh_installwm will install a slave manpage link for x-window-manager.1.gz, if it sees the man page in usr/share/man/man1 in the package build directory.
• dh_builddeb did not previously delete everything matching DH_ALWAYS_EXCLUDE, if it was set to a list of things to exclude, such as CVS:.svn:.git. Now it does.
• dh_installman allows overwriting existing man pages in the package build directory. In previous compatibility levels it silently refuses to do this.

This mode is deprecated.

• Comments are ignored in debhelper config files.
• dh_strip --dbg-package now specifies the name of a package to put debugging symbols in, not the packages to take the symbols from.
• dh_installdocs skips installing empty files.
• dh_install errors out if wildcards expand to nothing.

• dh_makeshlibs -V will not include the Debian part of the version number in the generated dependency line in the shlibs file.
• You are encouraged to put the new ${misc:Depends} into debian/control to supplement the ${shlibs:Depends} field.
• dh_fixperms will make all files in bin/ directories and in etc/init.d executable.
• dh_link will correct existing links to conform with policy.

This mode is deprecated.

• Debhelper config files support globbing via * and ?, when appropriate. To turn this off and use those characters raw, just prefix with a backslash.
• dh_makeshlibs makes the postinst and postrm scripts call ldconfig.
• Every file in etc/ is automatically flagged as a conffile by dh_installdeb.

This mode is deprecated.