Engadget
A refurbished phone can be the safer buy, but the word “refurbished” doesn't guarantee the same standard everywhere.
Especially as smartphone prices continue to rise, you can save an amount of money by buying one that's not brand-new. Not all used devices are the same. Two similar-looking phones might appear at the same price but with different labels, such as "pre-owned," "refurbished" or "certified pre-owned."
Broadly, the core difference is that "pre-owned" (or "used") is a description of the phone's history, while "refurbished" describes a process the phone has undergone. A refurbished device has usually been inspected, cleaned and tested, then repaired or fitted with replacement parts as necessary. A regular pre-owned phone, in contrast, is generally sold as-is.
Thus, all refurbished phones are used, but not all used phones are refurbished.
A used phone with buyer protection, a known history or remaining coverage can be just as sensible, and sometimes cheaper, than a good refurb.
A refurbished phone may have been restored by its manufacturer, an authorized refurbisher or a third-party company.
For instance, Apple Certified Refurbished iPhones come with a new battery and outer shell, and genuine Apple replacement parts are used as necessary. Similarly, Samsung's "Certified Re-Newed" phones (refurbished by the company) go through a 147-point quality inspection.
eBay's "Certified Refurbished" tier covers products refurbished by manufacturers or an authorized reseller and includes a two-year warranty serviced by Allstate. Its Excellent, Very Good and Good refurbished tiers come from "quality-vetted sellers" and have one-year Allstate-serviced warranties.
Verizon's CPO phones aren't passed from one owner to the next; they are inspected and reconditioned as needed.