The diff adds a new sentence saying Dell can delay giving you your money back until it has physically received your returned item. This is shown only as newly added text in this update — the diff does not show whether an identical statement already existed elsewhere on the page, so it should be treated as a new consumer-facing term rather than a simple restatement. In practice this means you may need to wait longer for your refund than just 'without undue delay' would suggest, since Dell can wait for the item to arrive first.
“Dell behoudt zich het recht voor om terugbetalingen in te houden totdat de goederen zijn ontvangen door Dell.”