File > Save As > (*.pdf) converts your SOLIDWORKS drawing to plain lines then, using proprietary code, saves it to a PDF.
This is a SOLIDWORKS function and is not relying on any third party to publish your PDF.
File > Print > (PDF writer) uses the SOLIDWORKS print engine to spool and communicates the information to your selected PDF printing software to produce the PDF.
SOLIDWORKS simply sends the information to the PDF writer or a virtual printer, and therefore the PDF writer is responsible for producing your PDF and not SOLIDWORKS.
For the examples below, I used CutePDF Writer (free), Adobe Reader DC (free), and SOLIDWORKS 2017 SP 3.0 (not free).
This was cropped from inside of SOLIDWORKS. It has the default drawing sheet paper color.
Tip: To change the drawing sheet paper color, simply go to System Options > Colors > Color Scheme Settings > Drawings, Paper Color > Edit.
Options
I used the default Save As PDF options.
Page Setup
For Scale: Scale to fit
Drawing Color: Color/Grayscale
Images
When producing PDFs that have images, it is best to Print to PDF. You don’t want those images being translated to plain lines.
You can clearly see the difference when comparing the penguins in both copies. The PDF writer handles images a lot better.
Lines overextending
Printing to PDF is notorious for overextending lines.
Most, if not all, automated PDF conversion tasks/macros use the Save As PDF feature. It forces a drawing to rebuild before producing the PDF. In a team environment with automated PDF conversion tasks, often times the PDF copies come out with undesirable changes. If any changes are made to the model(s) after the drawing is finished but before the conversion task kicks on, those changes will show up in the PDF. This has been known to do more harm than good.
PDM tasks also use the Save As function, which means you are susceptible to the rebuilding step mentioned above.
Both methods have their strengths and weaknesses. SOLIDWORKS has improved their internally-written code to produce those PDFs, but a lot of users still lean more on Print to PDF because they think of making PDFs as a printing process.
I’ll leave you with this; Save As PDF is a SOLIDWORKS feature and is supported by them—Print to PDF is not supported because it uses a third party software to create that PDF.
