I'll try dpkg next time I'm on Debian, to see comparisons with apt.
the apt tools are (at least in part) a front-end to dpkg. Another alternative is aptitude.
dpkg knows what to do with .deb files, but they have to be local. dselect is a curses GUI for dpkg.
apt knows how to find .deb files from the repositories, and how to ask dpkg to install them.
aptitude provides a curses GUI to apt, and also can keep track of dependancies at removal time.
synaptic is an X GUI for apt.
-jim
