Apple and Google both saw gains for their respective app stores over 2015, but each dominated one specific metric over the other. For Apple's iOS App Store, the biggest win was in revenue. Google's Play Store (Android) excelled in growth and market share.

The latest figures, comparing the success of iOS and Android's respective app stores over the last year, come from market data research and analytics company App Annie (via VentureBeat).

Last year, as the research firm stated on its blog, "was a banner year for the app ecosystem. Subscription monetization proved successful for video streaming, music streaming and dating apps. Games, ridesharing and [mobile] commerce also continued to grow in downloads and usage."

But among the myriad analytics the firm used to measure Google and Apple's ongoing digital software retail competition, only a couple of metrics really stood out as a measure of each company's success -- and for providing insights into how each Silicon Valley software giant differs in their digital retail strategies. 

Google's Android Rules Overall Market Volume

The Google Play Store saw a huge rise in downloads in 2015, according to App Annie's 2015 retrospective report, even compared to the considerable market share success Android's digital retail business showed in 2014.

"In last year's retrospective, we noted a 60 percent download lead of Google Play over iOS. This widened to nearly 100 percent in 2015. This massive disparity could mark the beginning of major changes in mobile marketing, including substantial increases of Android's share of mobile ad spend," the report commented.

The incredibly fast rise in worldwide downloads of Android apps is mostly attributed to emerging markets, including two Latin American markets that made the top five in global growth for Google Play's operations: Brazil and Mexico.

Put together, the two Latin American countries, along with Indonesia, India, and Turkey, accounted for nearly half of the year-to-year growth in Android app downloads. But interestingly, Google Play also passed iOS in U.S.-market downloads for the first time.

Apple App Store Revenue Growth Outclasses Android

At the same time, Apple's revenue from iOS purchases continued to outpace that of Google Play, even as both app stores made considerable gains in revenue, the report notes.

In 2015, Apple's iOS "cemented its position as app store revenue king," declared App Annie's retrospective analysis for the year. The App Store made over 70 percent more money than Google Play in 2015.

Much of the company's digital revenue growth was driven by strong growth in China, as well as healthy development in Japan and the U.S. Overall, those three countries contributed to nearly 90 percent of the Apple App Store's revenue growth over 2014. But the main underwriter of the App Store's standout expansion in 2015 was China.

In fact, the report notes that China overtook the U.S. in iOS downloads beginning in the first quarter of 2015, and it continued to lead into the new year.

Strong adoption of the iPhone 6 and iPhone 6 Plus by Chinese consumers was at the root of the ballooning iOS download and revenue figures for Apple, as the company's mobile user base in China grew roughly three times faster in 2014 than the market in the U.S.

That growth, of course, also enabled Apple at the beginning of last year to report the highest quarterly earnings for any company in history, generating about $8.3 million dollars of profit per hour, every hour, for Apple through that quarter.

Emerging Markets' Big Effect on Both

The takeaway from these two distinct, but major, gains for Apple and Google is that emerging markets are exploding app business for both companies, amplifying each company's strongest suit like never before.

Google is nearly doubling the audience for its ad marketing model, while Apple is nearly doubling the monetization of its iOS App Store.

How long the emerging market-led boom will continue fueling Google and Apple remains to be seen. But one particular operating system's app store continues to be practically invisible as Android and iOS burst into new markets: Windows.