With iOS 5’s primary feature set exposed and its underlying architectural upgrades detailed, we can now begin to draw comparisons between Apple’s latest offering and Google’s next-generation unified-tablet-and-smartphone Android OS, Ice Cream Sandwich. In many ways, iOS 5 pulls ahead of Android, with deep integration to the cloud and the unified iMessage service. If you twist the platforms and look at them with a different light, however, Android has tons of features that conjure jealousy and envy from the iOS camp.

Here are five ways in which iOS 5 stumbles behind its contemporary, Android Ice Cream Sandwich, and even the current versions of Android: Gingerbread and Honeycomb.

1. Home screen and widgets

One of the key features of Android is the functionality, flexibility, and usability of Android’s home screen and its widgets. Instead of being limited to standard, no-frills icons, Android home screens can be populated with various-size widgets, from clocks to weather updates to media player controls. The entire gamut of an Android device’s functionality can be viewed and accessed from the home screen — as opposed to the bland and spartan iOS, where all you can do is launch apps and create folders.

It’s worth noting that iOS 5’s notification area — which looks a lot like Android’s offering — has some widget-like features in the form of stock market and weather updates. Apple’s standpoint might be that a cluttered home screen isn’t a good thing — which is fair enough — but Android users with five completely-filled home screens will obviously beg to differ.

2. Flash

Love it or hate it, iOS doesn’t (and never will) support Adobe Flash. You can argue until you’re blue in the face about Flash’s poor performance on mobile devices, but the fact remains: Android can play Flash games and video, and iOS can’t. Most of the performance issues have been rectified with Flash for Android Honeycomb — and we can but hope that the experience is replicated with Ice Cream Sandwich on smartphones.

The bigger issue, though, is whether Flash is ultimately good for mobile computing as a whole. With iOS embracing HTML5 web apps, and Windows 8 seemingly going down a similar path, is Flash support really what the industry needs? It feels like a stopgap measure, to satisfy fans while Google (and RIM and Nokia and Microsoft) work on more powerful mobile web browsers.

3. Customizability

It’s hard to put into words just how customizable Android is — and to be honest, it probably deserves more than a mere catch-all in a list. Almost every core Android feature can be extended or replaced by third-party apps — and if that isn’t good enough for you, you can take the Android source code and roll your own operating system ROM, like the CyanogenMod team.

While iOS 5 will have Twitter functionality baked into every app, Android lets any third-party app link into any other app — including Android’s first-party music, camera, and messaging apps. With two clicks you can share a photo to Twitter… or to Dropbox, Picasa, or Flickr. With Android you can change your default browser to Firefox, or install a new input method; with iOS, Safari is your only option.

With iOS, customizability is an ideological concept that basically doesn’t exist, and iOS 5 won’t do anything to change that. While new versions of Android can be said to embrace and extend the functionality of third-party apps, Apple’s OS updates effectively steal from the likes of Fring, Instapaper, and Camera+, and give nothing back in return. In almost every closed system, app developers are inexorably squeezed out, and iOS is no exception — but hey, as long as it happens slowly and the majority of app developers can continue to make millions of dollars, who cares.

You could also lump hardware flexibility and expandable storage into this category, but I think we’ve said enough about Android’s superior customizability.