Use of Dialogs vs Activities

In android development, where a pop-up interaction with a user is required one can use in most situations either a "dialog" or a "activity. Excluding extreme cases where the choice is easy, I would like to know your ideas on which is prefered.

For ex. one might say that on screen orientation a dialog is lost and the user will have to do the same interaction to get it while an activity stays in place (of course it is "created" again but still stays in its place in the visibility stack).

I would like all possible issues for both cases (performance, side-effects, user interaction issues, etc...).