Emacs Modified for macOS and Emacs Modified for Windows are distributions of GNU Emacs bundled with a few select packages for R developers and LaTeX users, most notably ESS and AUCTeX.
Philosophy
The distributions are based on the official sources of GNU Emacs. Other than a few selected packages and some minor configuration, they are stock distributions of Emacs with a similar look and feel not only between them, but also with Emacs on other platforms.
The project started with the Windows version (probably around 2002 or so), when I wanted to provide my students with an Emacs fully setup for R programming and that would be easy to install — that is, distributed with an installation wizard.
The macOS distribution is based on Emacs for Mac OS X by David Caldwell. Those looking for a more Mac-like version of Emacs may consider Aquamacs, but be prepared to have Aquamacs play a lot with frames and fonts behind you. Furthermore, these days the development of Aquamacs is much behind GNU Emacs.
Author
Vincent Goulet, École d’actuariat, Université Laval