The mobile advertising network found that Android and iPhone consumers download approximately the same number of apps, and spend about the same amount of time using them. But about 50 percent of iPhone users buy at least one app per month, while only 21 percent of Android users do.

'Sheer Quantity and Variety'

The app-activity profile in the report could impact third-party developers and marketers, since platforms with the most-active and most-spending users could influence app-making decisions.

Avi Greengart, an analyst with industry research firm Current Analysis, said one of the reasons behind the higher purchases by the average iPhone user could simply be "the sheer quantity and variety of applications" offered in Apple's App Store.

"Developers have had more than a year to develop for the iPhone," he said. In particular, he said, entertainment-based apps have gravitated first to the iPhone.

But Greengart noted that the "tremendous variety and quality" of the apps extend beyond entertainment.

He said that, while in Barcelona recently for the Mobile World Congress, he was able to find and download an app to help him with the Barcelona Metro. "In fact," he added, "I had several to choose from."

iPod Users Younger

The survey also looked at users of Palm's webOS devices. It found that they are also app-active, although they downloaded fewer free and paid apps.

Owners of Apple's iPod touch were the heaviest app users, downloading an average of a dozen apps monthly. This is 37 percent more than either iPhone or Android users, who download only about nine per month. Users of webOS had an average of about six.

iPod touch users also spent the most time each day using applications, about 100 minutes on average. webOS users were in second place at 87 minutes, followed by Android at 80 and iPhone at 79.

The activity levels of the iPod touch compared to iPhone users could be age-derived. On average, iPod touch owners are 14 years younger than the iPhone user. Abut 78 percent of iPod touch owners are under 24.

Although older, owners of the iPhone are highly active. AdMob said about 47 percent of all smartphone usage in the U.S. in January was on the iPhone. Android devices were second at 39 percent, followed by Research In Motion and webOS devices, at seven and three percent.

As others have noted, Android owners tend to be overwhelmingly male, about 73 percent. iPhone OS users are more evenly divided, with 56 percent guys.

The survey collected the responses of about 960 users over a two-week period. RIM users were not included, since the advertising network currently does not serve ads into BlackBerrys. AdMob based its conclusions on usage of the more than 15,000 applications and mobile web sites in its network.