What's the difference between an “Edition” and a “Publication”?

Chirlu is corrected here - in fact we’ll be renaming publications to edition groups in the next release to avoid unnecessary confusion. So:

Edition = Release (a physical manifestation of a book or other literature)
Edition Group/Publication = Release Group (an abstract collection of editions that are fundamentally the same piece of literature, with minor differences)
Work = Work (an abstract entity representing some identifiable creative effort by a creator)