The critical difference is the latter pair are equipped with GSM (Global System for Mobile Communications) cellular radios only, meaning that they will work with networks like Rogers Wireless in Canada and AT&T in the United States.
It's debatable how accurate these commercials are, as they are clearly biased in favor of promoting Verizon over AT&T, but there are several personal accounts of dropped calls and poor coverage from AT&T subscribers.
The exclusivity deal with AT&T certainly helped to bolster its subscriber numbers, but this put an increased burden on the network and this may have led to some of the issues related to dropped calls and poor coverage.
Consumer Search breaks the phones down into "bests" based on categories like best business smartphone for AT&T users, top Windows Mobile device more business than fun, great Google Android phone for Sprint, and so on.
Popular cell phone providers are: Boost, Cingular (now AT&T Wireless), T-Mobile, Verizon, Sprint-Nextel, and Virgin Mobile, each of which offers different purchase plans, phone incentives, and package options.
The results of this sales suspension will shape Apple and AT&T policy for many years to come, as both companies attempt to develop pre-order policies that will benefit customers and the companies themselves.
If you're a Verizon customer and don't want to change, but desperately want to have an iPhone, you may find yourself holding your breath until at least 2010 and the end of the exclusivity contract with AT&T.
Fitting somewhere between the boldness of the magenta phone found at T-Mobile and the lighter colored version at Verizon is the middle-of-the-road pink RAZR from Cingular, which has now become the new AT&T.
While Verizon may be heavily pushing their "Can you Hear Me Now?" campaign, Cingular (and subsequently AT&T) quickly countered by saying that they have the fewest number of dropped calls across the country.
However, for many people living in major cities, all of the major carriers -- like AT&T and T-Mobile -- are also available and, as such, the issue of coverage may not be as important to these customers.