A missing page, two pages in the wrong order or a scan displayed upside down all concern the internal organization of a PDF, but they require different operations.
Extract selected pages
Extract PDF pages creates a new document containing only the pages you choose. It is useful for sending an appendix, isolating a certificate or creating a short excerpt from a larger report.
Reorder pages
If every page is useful but the sequence is wrong, use Reorder PDF pages. This is common after manual scanning or when a cover or appendix was inserted in the wrong place.
Rotate pages
A landscape page or an upside-down scan usually does not need extraction. Rotate PDF pages corrects orientation while keeping the page in place.