SAN FRANCISCO — Ever since Apple's iPhone went on sale in 2007, Verizon Wireless customers have held out hope that, one day, AT&T's grip as its exclusive U.S. distributor would be broken.

That day arrives next week, when Verizon's iPhone goes on sale. Verizon is accepting preorders from existing customers beginning today.

But even if it's the same phone, Verizon does things differently from AT&T, so there are some important factors to consider if you're thinking about getting one.

The big difference is likely to be network performance. AT&T's network is notoriously congested in some cities, including San Francisco, where for a week I tested both phones side by side. Out in the country, Verizon has much wider coverage for broadband wireless data.

The Verizon model was generally speedier at loading maps, websites and videos. I was already done watching a YouTube clip of an adorable sneezing baby panda on Verizon's phone when AT&T's finally gave up on loading the video. At times, I couldn't make a call on the AT&T iPhone but could easily do so on the Verizon one.

So Verizon was faster for me, but the situation could be the opposite in many places across the country. Where AT&T's network isn't congested, it's actually faster than Verizon's, at least where AT&T has made recent upgrades.

There are two other big changes.

Verizon's iPhone is the first to work on so-called CDMA networks, the type Verizon uses. AT&T uses GSM, a technology that's more widely used around the world. This means the Verizon iPhone has very limited international roaming abilities. It won't work at all in Europe.

Verizon's iPhone also includes Personal Hotspot, a Wi-Fi sharing feature that is becoming increasingly common on smart phones. It lets you connect as many as five gadgets to the Internet through the iPhone. If you're stuck without an Internet connection for your laptop, for instance, you connect through the phone and Verizon's cellular network.

The feature is easy to use, but there's a price for this convenience: $20 per month on top of what customers already pay for voice and data services. With voice, text and data plans, that could mean monthly bills topping $110.

But if weighing the pros and cons get to be too much, just remember that whether you buy it now or hold out for the next iteration, you're still getting an iPhone, silly.

And when it comes to smart phones, that's a smart decision.

<B>WHAT IT IS:</B> The Verizon Wireless version of Apple.’s iPhone will begin selling next week. It will cost $200 or $300 (depending on included memory) with a two-year Verizon contract.<B>THE DIFFERENCES: </B>On the surface, the Verizon iPhone is nearly identical to the AT&T version of the iPhone.A major difference will probably be network performance — AT&T’s network tends to be congested in some cities, while Verizon has wider broadband data coverage in rural areas. But where not clogged AT&T’s network can be faster than Verizon’s in some places.<B>ONE MORE THING: </B>Apple is likely to release a new iPhone model this summer, though it’s not clear if this would arrive at Verizon immediately. For some, this may make it even trickier to decide whether or not to pick up Verizon’s iPhone now.