view difference: ubuntu-desktop and other packages

[kabanta]

When I upgrade or reinstall the OS, it is useful to know what additional packages I have installed in the old/existing OS so that I can quickly install them in the new OS installation. Any tips how to do this?

I believe the default set of packages installed is ubuntu-desktop, so it would be nice to be able to see a listing of all my installed packages that are not part of ubuntu-desktop.

Alternatively, is there a way to sort the list of installed packages by date installed?

[dstew]

You can get the information you want, but I don't know how to do it easily. You can check in synaptic for installed packages. To get a list of all your installed packages you can do
dpkg -lUbuntu-desktop is all the packages for the graphical interface, but there are lots of packages in the base system too.