Suppose that (pseudo-)package A depends on (pseudo-)package B.I'm looking for a reasonable systematic way to answer the question: what would I get by installing A that I would not get by installing B alone?To put in the most abstract terms, I want to determine the difference between A's and B's dependency graphs.Is there a convenient way to do this with standard dpkg*, apt*, aptitude* tools?Since I'm interested in as general an answer as possible, I'm reluctant to give a concrete example (such examples tend to elicit answers that apply only to the example and not to the general case), but inevitably someone posts a comment asking for a concrete example, so here it goes:A could be task-xfce-desktop and B could be xfce4.Or A could be xfce4 and B could be xfdesktop4.EDIT: clarification (in response to Stephen Kitt's answer): I am indeed interested in the differences between the absolute dependency graphs (irrespective of the current state of my system).
How to determine the added value of installing a (pseudo-)package vis--vis installing only one of its dependencies?
debian;apt;dpkg