With a battery 16% larger than the last incarnation, technically, the iPhone 4's battery should have the edge but, of course, it doesn't really work like that. Both batteries are the size they need to be to run the components inside them from dawn till dusk. Smartphone designers tend to be looking for a one heavy day's use on a single charge. We already know that the Desire provides this. That said, Apple are claiming a bigger battery over the 3GS and improvements with the A4 processor. That means that while it offers a longer call time (half an hour), the HTC Desire wins out on standby.
Tie: Iphone vs. Desire
Both phones have a very similar spec under the hood with 1GHz processors at the helm. While the iPhone has Apple's ARM Cortex A8, the Desire uses Qualcomm's Snapdragon platform. They're designed in different ways, but both offer the kind of performance you need in a top end-smartphone. Some might point to the additional RAM used in the Desire as an advantage but that just seems to be the extra that's needed to power the HTC Sense UI on top of Android. Of course, we might find that the A4 processor is underclocked in a way that Apple has previously done in order to save battery life in which case, we'd have to hand the category to HTC.
Tie: Iphone vs. Desire
The screen is one of the most important battlegrounds when you're talking about touchscreen smartphones and the small advantage the Desire has over the iPhone is that it's bigger and not by an awful lot either. A 3.7-inch display is a significant advantage but ultimately, it pales to the quality offered by Apple - certainly on paper, anyway. The higher resolution and pixel density on the iPhone screen and while it lacks AMOLED, that Retina display should, says Apple, replicate reading on paper, magazine paper rather than newspaper we presume.
The other point of interest is that the iPhone uses an LCD rather than an AMOLED. While the AMOLED might use less power and have arguably better video performance, it's not as good in sunlight. You can whack the brightness up to an acceptable level when you're outside but if you're having to to take a photo with the sun to you back, then you won't see a sausage.
iPhone - 3.5", 960 x 640, 326dpi, TFT-LCD
Desire - 3.7", 480 x 800, 240dpi, AMOLED
Winner: iPhone
