The difference between a Raster and Vector PDF is pretty clear when you open the PDF File in eg Acrobat Reader. You can tell the differences in the following ways
When you open a Raster PDF File, you will typically see that it loads graphically from bottom to top or left to right, as if it is painting one row or column of pixels at a time. Once opened if you zoom in, you will see that the linework is pixelated and not sharp at all. You will also often see in the white space around the linework that it is off white and maybe has speckles (pixels) that look like dust on the drawing - this is because a raster PDF is typically created by scanning a document or drawing rather than printing to PDF which will generally create Vector PDFs more like a CAD drawing. Raster PDFs are typically larger in size than vector PDFs. The Colored Fills like a Cut Fill Map or Ortho Photo in a PDF are always going to be Rasterized. The Linework and Text are typically the part that can be Raster or Vector. These days it is more common to receive Vector PDFs than Raster PDFs for Plans, Sections and Profiles.
Typical Raster PDF - Zoomed In View
When you open a Vector PDF it typically opens quickly and typically looks clean and sharp. The background is typically pure white and there will be no speckles whatsoever. The linework will look sharp and crisp, no matter what zoom factor you are at. Vector PDF files are created in a similar way to a pen plot process, where the colored pen traces out the linework of a drawing vs an ink jet or laser printer where the drawing is rasterized and printed line by line of pixels to the paper.
Typical Vector PDF Drawing - Zoomed In View
The benefit of a Vector PDF is that you can typically extract the vector lines out of the PDF pages once they have been georeferenced and use them to reconstruct 2D linework that can be used as the basis for Takeoff Modeling.
Note that because you georeference PDF files (that places them, scales them and rotates them) and because you extract the vector linework which is not as accurate as CAD linework, while suitable for Takeoff / Estimating purposes, they are not suited to Data Prep for Machine Control applications. Data for Machine Control needs to be as accurate as possible and typically you will need either the CAD files or you will need to reconstruct the data using the data provided on the plans from scratch to achieve the accuracy that you require.
Example Raster PDF File
670021-0000-4GDM-0001_00 7.pdf (5.4 MB)
Example Vector PDF File
Audubon Heights 7th Addition.0909.pdf (15.8 MB)