What's the relationship between ~foo~ and =foo= in org-mode?

Question

Both =foo= and ~foo~ seem to be used in org for inline bits of code. How do they differ? Which should I use, and when?

For example, from the ORG-NEWS file:

If you want to exclude a headline from export while using its contents
for setting options, use =:noexport:= (see =org-export-exclude-tags=.)

...

The key sequences =C-c C-n= and =C-c C-p= are now bound to
~org-next-visible-heading~ and ~org-previous-visible-heading~ respectively,
rather than the =outline-mode= versions of these functions.  The Org
version of these functions skips over inline tasks (and even-level
headlines when ~org-odd-levels-only~ is set).

There isn't an obvious pattern here: org-export-exclude-tags and org-odd-levels-only are both variables, and org-next-visible-heading and outline-mode are both functions.

Do either of these syntaxes support jumping to *Help* buffers the way `foo' does in docstrings?

Answer 1

From the Org info page on "Emphasis and monospace" we have

`=verbatim=' and `~code~'

In your examples the functions and variables are pieces of elisp code, so ~...~ is appropriate. The uses of =...= you cite are for key sequences and text for the user to place in the org buffer, i.e. markup rather than code. However, the markup of =outline-mode= is borderline between the two categories.

Answer 2

It's suitable to interpretation. I've been redefining e.g. ~C-f~ to export to <kbd>C-f</kbd> in HTML, and e.g. =forward-char= to <code>forward-char</code>.

(setq org-html-text-markup-alist
      '((bold . "<b>%s</b>")
        (code . "<kbd>%s</kbd>")
        (italic . "<i>%s</i>")
        (strike-through . "<del>%s</del>")
        (underline . "<span class=\"underline\">%s</span>")
        (verbatim . "<code>%s</code>")))

But their default names are indeed code and verbatim, just like the other answer says.