What is the difference between Export as PDF and Export > Format: PDF (Preview)

Recently I drew a simple line on a blank page in Preview. I realized, that if I export the Document via File > Export as PDF, and open the exported Document, I don't have the ability to move around and edit the line. If I alternatively use File > Export and then choose 'Format: PDF' I can edit the exported file later. So this lead me to the question, why there are 2 different PDF Export 'Formats' in Preview. I believe that this might pose a slight security risk, since editable PDF Documents can later be manipulated.