# diff-pdf > Compare two PDFs. > More information: . - Compare PDFs, indicating changes using return codes (`0` = no difference, `1` = PDFs differ): `diff-pdf {{path/to/a.pdf}} {{path/to/b.pdf}}` - Compare PDFs, outputting a PDF with visually highlighted differences: `diff-pdf --output-diff={{path/to/diff.pdf}} {{path/to/a.pdf}} {{path/to/b.pdf}}` - Compare PDFs, viewing differences in a simple GUI: `diff-pdf --view {{path/to/a.pdf}} {{path/to/b.pdf}}`