What is the difference between each of the following.
Emacs snapshot is the CVS version of Emacs. GTK is compiled with GTK support. NOX means compiled without X support. vNN are the version numbers.
Note the latest stable release of GNU Emacs is 23.1. emacs-snapshot is the closest to this.
The number denotes which version of emacs - so v22, v21, etc.
NOX denotes that the release doesn't have X Window Support (I would imagine that it would thusly be CLI only).
Snapshot .. not sure, but it probably is a snapshot in between revisions of the software.
GTK is a library for building GUI's - this is a gui release of emacs.