Q: What is the difference between the AFPL and the Ghostscript version of PDFCreator?
A: The main difference is the Ghostscript version used. The AFPL version is newer than the GPL version, but the license is more restrictive. If you just want to use PDFCreator, then both versions are fine and the AFPL should be prefered, as it is far better. If you need an aspect of the license, that is not covered by the AFPL but by the GPL, then you should download the GPL version.
Q: What file should I download?
A: PDFCreator requires Ghostscript. There are 2 different Setups for the two versions of Ghostscript.
This Setup contains AFPL-Ghostscript and is the recommended version. The AFPL version is more recent than the GPL version.
This setup contains GPL-Ghostscript. It might be required by problems with the license, that the GPL version has to be used. But beware, that the printer monitor contains files, which still are released unter the AFPL.
The complete source code of PDFcreaor.
This setup does not contain Ghostscript at all and can be used, if the latest version of Ghostscript is already installed. PDFCreator detects local installs of Ghostscript. But beware, that it still contains the printer monitor, which contains files, that are released unter the AFPL.