Merging PDFs vs. Printing to One PDF: What's Actually Different
Merging combines the original PDF pages directly, preserving their exact original quality, embedded text, and structure. Printing multiple documents to a single new PDF re-renders each page through the print process, which can degrade image quality, lose embedded selectable text (turning it into an image instead), and increase file size — merging is generally the better approach specifically when the source files are already PDFs.
These two approaches can produce a visually similar result, but the underlying quality and structure of the output can differ meaningfully.
What merging preserves
Because merging combines the actual underlying PDF page data rather than recreating it, embedded selectable text stays selectable and searchable, images retain their original resolution, and any interactive elements (like form fields) are generally preserved — the merged file is structurally close to the original source files, just combined.
What printing-to-PDF can lose
Printing existing PDFs to a new single PDF (using a virtual print driver) re-renders each page as it goes through the print process — this can flatten selectable text into a static image (breaking text search and copy-paste), reduce image quality if the print settings aren't set to full resolution, and often produces a noticeably larger file for the same visual content.
When printing-to-PDF is actually necessary
For combining a mix of file types (not just existing PDFs) into a single PDF — a Word document, a web page, an image — printing to PDF (or a dedicated conversion step for each) is often necessary as part of the process, since there's no existing PDF structure to merge directly. For combining files that are already PDFs, a direct merge tool is the better, quality-preserving choice.