What is a used iPhone?
A device sold directly by its previous owner, without technical review or legal warranty in sales between private individuals.
What is a refurbished iPhone?
It has been through specialized technicians: complete diagnosis, parts replacement, cleaning, grade classification, and includes a commercial warranty.
The 5 risks of buying second-hand
Degraded battery, iCloud locked, invisible internal damage, unknown history, no legal recourse if it fails.
Is there really such a big price difference?
The difference is usually €50 to €100. It is justified by the peace of mind of having support if something goes wrong.