Use PDF for a static handout
A PDF can make it easier to share slides with someone who needs to read or print them without editing the presentation. Each page presents a slide as a static view. This is useful for review notes, leave-behind material, or a record of what was shown at a particular point in time.
Keep the PPTX when the recipient needs to change slide text, reorder sections, or present animations. The editable deck contains more than the final page images: it may include transitions, speaker notes, embedded media, and objects arranged for live delivery.