Despite the constant moaning from Steve Jobs about how AT&T's version of the iPhone 4 was perfect, had no antenna problems, and didn't need any tweaking, it looks like Apple decided to "fix" it anyway. Research firm iSuppli has found some major changes to the device for its change to Verizon. Of course, the innards are quite different because Apple needed to swap out the GSM chip that powers AT&T's mobile network to something that could accommodate Verizon and its CDMA spectrum. But many of us assumed the front end of the iPhone 4 would remain relatively unchanged. And I personally believed Apple was too stubborn to even touch the phone's antenna, mainly because Jobs kept telling everyone there was nothing to fix.
According to iSuppli, which performed a complete teardown of the Verizon iPhone, there is a new "dual-antenna design that takes advantage of antenna diversity to improve reception."
Verizon had mocked Apple last year because of the widely publicized iPhone antenna problems, boasting that its Droid X had a "double antenna design." Lo and behold, it was able to incorporate that same design into the iPhone. In some small way, this must mean Apple admitted there was fault with its previous antenna design, so the world should take note of this moment.
Additionally, the Verizon version of Apple's phone gets rid of the separate GPS chip that was used for AT&T and uses an integrated GPS found built-in to Qualcomm's MDM6600 baseband. This will have little affect on the end user, though.
Aside from that, the device appears to be nearly identical to the one AT&T customers have been using for several months. That is to say, if you see two people walking down the street with an iPhone 4, you won't be able to immediately tell which one is using Verizon and which one is using AT&T.
However, when you see one complaining to customer support or holding the phone out in front of them to realize the call was dropped, you'll know that was the AT&T phone.