Is this Debian or a Debian-based system, or a RedHat-based distro ?????
Assuming Debian/Ubuntu like your profile says:
dpkg --get-selections | grep "[^e]install" > /tmp/pkgs.txt
or, for more details:
dpkg -l | grep ^ii > /tmp/pkgdetail.txt
Run one of those on both. Then transfer one of the files over and use "diff file1 file2" to compare the two files.