The smartphone operating system is increasingly becoming a two-horse race. Apple (Nasdaq: AAPL) iOS and Google (Nasdaq: GOOG) Android grow their collective share each and every quarter and now power four out of every five smartphones sold in the world today.

With Android's share towering at 56.1% while iOS lags with 22.9%, you might think that major version updates to Android are more important that for its rival from Cupertino. Both companies unveiled the next major versions of each respective operating system, iOS 6 and Android 4.1 Jelly Bean, last month, but iOS 6 is much more significant than Android 4.1.

I'm not even referring to new features or functionalities being included in the newest versions. Rather, it all comes back to what's frequently cited as Android's biggest weakness: fragmentation. There are many layers of this, one of which involves slow rollouts and software update delays within the Android army as each hardware manufacturer and carrier has to sign off.

It's a constant guessing game for Android users when -- or even if -- they'll get the newest versions of the operating system whenever they get updated. At Apple's Worldwide Developers Conference in June, iOS chief Scott Forstall said 80% of iOS users are now running iOS 5, the latest publicly released version. As of the beginning of July, Android 4.0 Ice Cream Sandwich was installed on just 11%, according to Google's Android developer site.

Both versions were released in October of last year, so they share an approximate starting point for adoption. This is why updates to iOS are more meaningful, because iOS users will actually get to use all the features in the first place. Only a tenth of Android users even enjoy features in Ice Cream Sandwich eight months after release, so who knows when they'd get a crack at those in Jelly Bean unless they go out and pick up a new Nexus 7 tablet.

In fact, 64% of users still use Android 2.3 Gingerbread, which was released in in 2010. It's worth noting that Google measures version distribution based on what Android devices access its Google Play content store. That means that Amazon.com's (Nasdaq: AMZN) Kindle Fire, which runs a heavily modified, or forked, version of Gingerbread, isn't even included in that figure because it points to Amazon's own Appstore instead of to Google Play. Since the Kindle Fire is technically an Android device, that means that the percentage of users on Ice Cream Sandwich is even slimmer than what's reported.

iOS 6 is more meaningful simply because it will reach more of its user base quickly.

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