The Emacs mailing lists are described at the Emacs Savannah page. Some of them are gatewayed to newsgroups.
The newsgroup news:comp.emacs is for discussion of Emacs programs in general. The newsgroup news:gnu.emacs.help is specifically for GNU Emacs. It therefore makes no sense to cross-post to both groups, since only one can be appropriate to any question.
Messages advocating “non-free” software are considered unacceptable on
any of the
gnu.* newsgroups except for news:gnu.misc.discuss,
which was created to hold the extensive flame-wars on the subject.
“Non-free” software includes any software for which the end user can't
freely modify the source code and exchange enhancements. Be careful to
gnu.* groups from the ‘Newsgroups:’ line when
posting a followup that recommends such software.
news:gnu.emacs.bug is a place where bug reports appear, but avoid posting bug reports to this newsgroup directly (see Reporting bugs).