A recent study from London-based GlobalWebIndex reveals that Google+ tops Twitter in terms of popularity with smartphone app users worldwide.

The study places Google+ at number 4 behind Google Maps, Facebook, and YouTube. Twitter comes in at number 6, right behind Weixin/WeChat.

Here are the top 10 in a nice infographic from Mashable. But what exactly do the numbers mean?

Studies of social network usage often require a rather literal interpretation.

For example, fans of HootSuite and Echofon might argue that the GlobalWebIndex study doesn’t appear to take into account third-party Twitter apps. If this is the case, do the study results really indicate that smartphone owners are spending more time on Google+ than Twitter? Or simply that more people are using the Google+ mobile app than Twitter’s own in-house app?

The literal nature of social media usage studies is often cited when discussing results that, at first glance, show Google+ pulling ahead of Twitter in terms of overall users. As Media Bistro points out, it’s possible that the numbers of Google+ users are inflated because they include people who have a Google account in order to use Gmail or YouTube, but are rarely or never active on Google+.

However, tying the GlobalWebIndex study into the great Google+ versus Twitter debate, if someone goes to the trouble of downloading the Google+ app on their smartphone, it’s probably safe to assume that they’re actually planning to get on Google+ instead of merely checking email or watching YouTube videos.

What about you? What social network smartphone apps do you use most often? Let us know in the comments.

Image credit: Google+ icon, chart