emacs without suffix is the GTK+ version of Emacs
emacs-nox with the
-nox suffix is the emacs version without the X server support.
emacs-lucid with the
-lucid suffix includes the Emacs with a Lucid user interface.
Now the question is "What is the Lucid interface?" Certainly the package description isn't helpful in this case. Fortunately I found a bug report that tries to fix that:
But what is a Lucid user interface? Presumably it means "the user
interface offered by emacs23-lucid", which is still unhelpful.
The changelog.Debian.gz tells me it is "an emacsVER-lucid package for
those who still want the non-GTK+ version" --- that is, the UI
(1) looks like old emacs
(2) does not use GTK+
--- which seem like useful data for a person deciding whether to install it.
The reader is also curious about the relationship, if any, to Lucid,
Lucid, Inc's "Lucid Emacs" was the fork that became XEmacs. So it would seem that emacs23-lucid is the version of GNU Emacs designed to
look like nineties versions of XEmacs? See
Installing them and comparing (on Squeeze) I see that emacs23's splash
screen says "This is GNU EMacs 23.2.1 (x86_64-pc-linux-gnu, GTK+
Version 2.20.1)" while emacs23-lucid's has "(x86_64-pc-linux-gnu, X
toolkit, Xaw3d scroll bars)". It's older and greyer-looking than the
GTK+ version, but nowhere near as grey as xemacs21...
And then what we hopefully will see as the next description (which seems clearer):
Maybe the description could be something like:
Description: The GNU Emacs editor (non-GTK+ GUI) GNU Emacs is the
extensible self-documenting text editor. This package contains a
version of Emacs with a graphical user interface based on the old
XEmacs-style Lucid widget set.
You can know more about this "Lucid" here.