Because Windows Phone 7 supports neither copy and paste nor multitasking, you cannot select text or graphics and copy them elsewhere, such as in emails. You can share the URLs of Web pages via email or SMS. The iPhone supports copy and paste, as well as URL sharing.
Both OSes lets you open multiple Web pages, but you can view just one at a time. Windows Phone 7 uses one field for searches and URL entries, whereas the iPhone has one field for each. I think both approaches work just fine.
The two OSes let you bookmark Web pages and add Web pages to your home screen (called "pinning" in Windows Phone 7), but only the iPhone lets you place them in bookmark folders. Bookmarks are one big list in Windows Phone 7.
Neither device supports Adobe Flash. Microsoft has suggested it will do so in the future. Apple of course has no plans to allow Flash support, given Apple's dislike of the Adobe Flash technology.
In a misguided effort to promote other Microsoft products, Windows Phone 7 provides only the Bing search engine, whose results are not always great. The iPhone lets you choose among Google, Yahoo, and Bing. (Google has made a Google Search app available in the Windows Phone Marketplace.)
But a nice capability in Windows Phone 7 is its ability to report itself to websites as a desktop browser, for those times you don't want the site's mobile-optimized pages, through a simple settings control for Internet Explorer. I wish the iPhone could do that to avoid some of the horrible mobile sites out there.
I also like the voice-recognition capability in Bing. It's pleasantly accurate in letting you search the Web via voice -- even more accurate than Android's similar feature. The iPhone can't search via voice recognition.
The winner: The iPhone, thanks to its support of HTML5, broad search engine support, and ability to copy text and graphics.
Deathmatch: Location support
Both the iPhone and Windows Phone 7 support GPS location, and both can triangulate location based on Wi-Fi signals. As noted earlier, the iPhone's maps app is better than Windows Phone 7's, though both are serviceable.
Although both the iPhone and Windows Phone 7 ask for permission to use your location information, Windows Phone 7 does not provide controllable settings for location use by the device or individual applications, as the iPhone does. (Windows Phone 7 does let you enable location detection to influence its search results, but that's not about helping you manage your privacy, as the iPhone's capability is.)
The winner: The iPhone, for its better maps app and its ability to control location privacy at a granular level.
Deathmatch: User interface
Even in its early preview versions, it was clear that Windows Phone 7 had an elegant, simple, and usefully different interface. In many ways, it's even simpler than Apple's iOS. It also borrows many UI techniques from the iPhone -- its gestures, its home screen management, and its email management -- and some UI techniques from Android, such as its menu buttons.
I found it easy to use Windows Phone 7 -- about as easy as iOS, in fact, despite differences in their approach. Windows Phone 7, for example, makes you scroll vertically, whereas the iPhone scrolls horizontally. Windows Phone 7 uses "more" (the ... icon) pages for less accessed tasks, whereas the iPhone finds a way to include them or doesn't bother with them at all.
Sometimes, though, the Windows Phone 7 interface is too spare, as if designed by a Steve Jobs wanna-be. The result in some panes, such as the browser's Favorites list and the calendar's list view, with large readable text on long lists that are hard to navigate or parse. Other UI elements cry out for more differentiation. The panels on the home screen, for example, are so similar it's hard to find what you want. They're also bigger than need be, forcing more scrolling than necessary (yes, you can and should rearrange them).
However, the iPhone does more than Windows Phone 7, and Apple's designers have excelled at building interface controls that are invisible until required or until called by a gesture. I haven't yet encountered similar UI approaches in Windows Phone 7, which will need such nuance if it adds more capabilities over time.
Windows Phone 7 is good about not getting in your way as you use the device. As with the iPhone, Windows Phone 7's onscreen keyboard disappears automatically when you click outside of a text field.
The iPhone does a slightly better job of providing visual feedback, though Windows Phone 7 does a good job here too. For example, when you tap and hold to insert the text cursor, the iPhone shows you a zoomed view of your selection area, whereas Windows Phone 7 merely places an icon above your selection point.
Both the iPhone and Windows Phone 7 let you double-tap the Shift key to get a caps lock. Both display accented characters and symbols in a pop-out menu when you tap and hold some keys. Windows Phone 7's symbols keyboard includes a bullet character -- a nice addition -- but in doing so buries the asterisk (*) key. Once you find it, you're OK, but it would've been better if Microsoft had stuck with the standard QWERTY symbol layouts and added the bullet to an unused location instead. Windows Phone 7 also has a whole keyboard of emoticons, a nod to social networking users.
Pinching, zooming, and scrolling, as well as autorotation as you turn the device, work equivalently on the two mobile OSes.