A report and a poster can look similar on screen while using different document structures in Pages. Before changing the type, determine where the text actually lives. A body paragraph and a text box do not have the same conversion behaviour.

Keep an untouched copy of the document and work in a separately named conversion copy. Note the first and last paragraph, important inline images and any text boxes. These are the items you will compare after conversion.

Inspect the document type

In Pages on Mac, click Document in the toolbar and inspect Document Body. A selected checkbox indicates word processing; an unselected checkbox indicates page layout.

Apple warns that converting word processing to page layout deletes body text and objects that move inline with that text. Objects set to stay on the page remain. Preserve the body content and inline objects before clearing Document Body; Apple describes copying them and pasting into a text box after conversion.

The reverse conversion retains existing objects, including text boxes, but may require adjustments to layering and wrapping. Turning Document Body on should therefore not be treated as a promise that separate text boxes become one flowing report.

Validate the new structure on the copy

Make the intended checkbox change in the working copy, reading any confirmation carefully. Restore preserved content to suitable text boxes where required. If the result is unexpected, use Command-Z promptly or return to the untouched copy.

Compare the content inventory, not just the page count. Check paragraphs that originally crossed a page boundary, captions beside images and objects that overlapped. Then try a small edit at the beginning and observe whether the rest of the document behaves as you intended.

If the task is only changing a heading, margin or picture position, reconsider whether conversion is necessary. Keep the source version until the new layout has been checked in full. A visually attractive first page does not prove that the original report survived the structural change.

References: Apple: Pages template types and conversion.