As far as I know GP4 files are bit-map/raster images, so they are not very useful in CAD software. SW does not know how to import GP4 files.
The PDF file may be slightly more useful, depending on whether or not it is also a PDF bit-map/raster image. If the PDF is a 2D or 3D vector image then it may be a little more useful.

Here is a link to an explanation on how to tell the difference easily:

http://visual-integrity.com/faqs/spo...or-raster-pdf/