There are three different flavors of the Ghostscript PostScript interpreter, released under different licenses:

GPL Ghostscript: Free software released under the GNU GPL. This flavor is included in Debian as the "gs-gpl" package.

ESP Ghostscript: Free software released under the GNU GPL. This version of Ghostscript is maintained and enhanced by Easy Software Products et. al., and supposed to be well-suited to the CUPS. This flavor is included in Debian as the "gs-esp" package.

AFPL Ghostscript: This flavour is the more current and more up to date one but under a license that is not DFSG-free. If you want to use this package please make sure that you agree to the license. The AFPL variant of Ghostscript is not part of the official Debian distribution but we provide a package for it in the non-free section as a service to our users. This flavor is called the "gs-afpl" package.

This package contains the common files among these flavors for managing the font installation and some wrapper scripts.