Difference between `gnus-summary-make-false-root' and `gnus-build-sparse-threads'

Difference between `gnus-summary-make-false-root' and `gnus-build-sparse-threads'

[Garreau, Alexandre]

I’ve never really well understood `gnus-summary-make-false-root', but
maybe this is only me, yet I’ve kind of more understood
`gnus-build-sparse-threads', but am still failing at seeing in what they
refer to different things:

Aren’t both about making up a almost void line in Summary buffers so
when messages both reply to the same message, which you don’t have in
your buffer, they are indented relative to it, which is guessed to be a
reply to messages you might have according common References, right?

I’m trying of reading help-gnu-emacs like it is displayed in the web
archives, to see if I can find messages posted from newsgroups with a
common parent while not being one in reply of the other, to inspect if
they both have the same references so to better understand the reference
garbling in the GNU newsgroups–mailing-list gateway that breaks threads.

`gnus-build-sparse-threads' seems to do what’s expected, but then I
recall `gnus-summary-make-false-root' was way better advertised in
manual than `gnus-build-sparse-threads', so I don’t get why, and what it
is for, then.

PS: I still only use Gnus for mail, so I may be unaware of
newsgroup-specific stuff, but I’m willing to begin some days.