I just successfully unlocked an old AT&T iPhone 4 and 4S using AT&T's unlock process. They are not jailbroken. As I've gone online to sell the phones, the selling phrase is "Factory Unlocked." Is there any difference between factory unlocked and my successful "carrier unlock"? If so, what are the differences?
Yes, there is a bit of a difference, though I largely agree with bmike. I guess I should add that while there might not be a difference in the outward functionality of the phone, there are differences between the phones provided by carriers, the procedure used to unlock those, and the unlocked iPhone sold by Apple.
This past July, I went through the same unlock procedure that you did when my wife's parents gave her an iPhone 4S that was sent to them by AT&T via an insurance policy that replaced a phone they believed was lost. Anyway, their phone was located right after the new one came in the mail, so they gave it to her. The problem was that we are on Verizon, so we couldn't use the phone. I wrongly believed it was the "world" iPhone that Apple sold, so I went through the process of getting AT&T to unlock it. Unfortunately for me, I didn't pay close enough attention to the rear of the packaging, which clearly indicated that this was a GSM-only phone. Undaunted, I called the nearest Apple Store to arrange an exchange for a CDMA phone - a simple enough thing, right? After all, it was still in the shrink wrap. I spoke with the store manager, gave her the serial number of the phone, and was shortly informed that this was not a phone stocked by Apple stores. The kind of phone I had was marked to be sold only by AT&T, either out of their retail establishments or shipping centers. I called AppleCare, and they informed me of the same thing. As it turned out, no one would even accept a brand-new, still-in-the-shrink-wrap, Apple iPhone 4S. Apple could not take it's own, brand new product in return for an essentially identical device. Only AT&T could accept it as a return, and they obviously didn't have any CDMA capable phones to send in exchange. Ultimately we sent the phone back to my in-laws, and ended up purchasing our iPhone 4S devices directly through Verizon.
To add to all this as sort of a general FYI, the unlocked iPhone sold by Apple is not the same thing as the "world" model, either. From Apple's Web Site regarding the unlocked iPhone:
And here is the info for the "world" iPhone from the "tech specs" page:
The reason for posting all of this is both as a response to your question and as a general information filter for prospective buyers.
No. Both mean that the carriers have agreed that this device will be registered into a database that Apple uses to unlock the device when it gets restored and powered on the first time (and the first time after major software upgrades).
I suppose some people say Factory unlocked when it is sold with a carrier unlock and the latter can be accomplished at any time if it is originally sold to a consumer as carrier-locked.
Someone buying wouldn't care either way since the devices work the same and would both still be unlocked if you took either to Apple for an exchange service if it needed a repair.