Technically, they are divided into four categories: Used, Refurbished, Certified Used, and Certified Refurbished.
A Used phone means that the phone is used and sold as-is. It's the most common term being used in eBay, Craigslist, Facebook Marketplace, OfferUp, and other marketplaces. Because of the popularity of this term, even professional sellers or merchants may use the same term, although their products are technically Certified Used phones or Certified Refurbished phones.
A Refurbished phone means that the phone is used and has been refurbished to a sellable condition. To clarify, "Refurbishment" doesn't always mean opening up the phone and repair. Sometimes it may refer to basic cleaning without disassembling the phone.
A Certified Used phone means that the phone is used and has been certified by a professional seller or merchant. The certification requires a rigorous inspection process to ensure all functionalities work fine. The test items include but are not limited to Power, Display, Touchscreen, Cellular, WIFI, Sensors, Speaker, Receiver, Bluetooth, Charging Port, Audio Port, etc. In addition to the functionality test, it also runs the background check to make sure the phone is not blacklisted, lost or stolen, or still under a finance plan. That guarantees you a fully functional and safe-to-use phone. Remember, a Certified Used phone should only come from a professional seller. All phones listed on UpTrade are Certified Used or Certified Refurbished. So if you see some person claiming that they have a Certified Used phone for sale on Craigslist or other open marketplaces, it's probably not true.
A Certified Refurbished phone means that a phone is used and has been refurbished by a professional seller. Same as Certified Used phone, Certified Refurbished phone also requires a rigorous inspection process. There is no real difference between Certified Used and Certified Refurbished. Some professional sellers prefer using the term Certified Refurbished phone, and others like another.
Last but not least, pay attention to the seller instead of the term. Each seller may have its definition and use the words differently. As long as the phone is being sold by a reputable professional seller, it doesn't matter whether it's called Used, Refurbished, Certified Used, or Certified Refurbished. The quality of the phone is good. Vice versa, getting a phone from an open marketplace or someone you don't know is risky. No matter how highly they say about the phone, you still risk getting scammed. Therefore, at UpTrade, we felt the necessity to have a marketplace showing the products from Reputable Professional Sellers and Merchants only. So you can rest assured of finding a good deal on a used phone with excellent quality at UpTrade.