B&N Classic comes with foot notes, additional comments, translator notes, etc... Usually the quality of their public domain books is pretty good.
Most of what is in PD is just the translated work and that is all, and the quality of the format varies. So far, albeit I've only seen a few, most of B&N Classic eBooks are pretty well formatted.
Since they are free, I'd recommend you download a book and check them out to see the difference.
=X=
|