Interface and functionality:
The iOS 6 interface of the iPhone 5 bets on simplicity and doesn't get much in the way of launching apps, whereas the HTC Sense 4+ UI over is a full-fledged manufacturer overlay over Android Jelly Bean's stock looks.
HTC Sense is more versatile not only in functionality, but also has pretty polished looks that are graphically consistent throughout the menu levels, like in iOS, which can't be said for many Android manufacturer overlays.
Processor and memory:
The 1.7 GHz quad-core Tegra 3 of the HTC One X+ can't be directly compared to the dual-core A6 chip inside the iPhone 5, except in browser benchmarks and graphics tests, where Apple's silicon scores more.
A more important takeaway here is that you won't feel underpowered with either of these two, and each runs the respective interface and apps from its ecosystem without any hiccups.
The phones offer 1 GB of RAM, which suits them fine, but the true multitasking advantage of Android over iOS is somewhat lost on HTC One X+, as it doesn't allows more than to run 8 apps at once, closing the initial ones automatically if you launch more.
A very generous 64 GB of internal storage amount awaits you with the One X+, whereas a 64 GB version of the iPhone 5 will run you pretty penny, and both phones don't offer storage expansion via memory cards.
Internet and connectivity:
Both stock browsers won't give you any trouble rendering pages quickly, panning around them, scrolling and zooming in. Safari on the iPhone 5 has a more limited scrolling inertia compared to the Android handset, but its makes a tad more fluid impression in other navigational tasks.
The browsers of the One X+ and the iPhone 5 have a one-tap reading mode next to the address bar, which devoids the articles of ads clutter and other distractions, leaving you with clean text to read comfortably.
HTC, however, has embedded full Adobe Flash support in its browser, which has a convenient toggle in the context menu, so if you come across a place where Flash is needed, the option is there for you.
The handsets support LTE connectivity on carriers that offer such networks, and also have 42 Mbit/s HSPA+ radios. Other wireless connectivity options include Wi-Fi, Bluetooth 4.0, A-GPS and DLNA, while the One X+ throws in FM Radio and NFC. HTC's handset uses an MHL port for wired connectivity, where you can plug a regular microUSB cable, whereas the iPhone 5 has its new proprietary Lightning connector for hooking up to computers and accessories.