That's an interesting question. I would, generally speaking, refer to the names of books, journal articles and magazines as their titles, not headings.
'Heading' I'd probably use to describe the names of chapters in a book or, more usually, sub-headings (being the shorter names of subsections found in texts.)
Headlines are what titles of news articles are called.
So the differences between them? Headings and headlines are all titles, but not all titles are headings or headlines.
I think.
Hopefully that makes some amount of sense.