TapTapTap’s best-selling iOS photo editing app Camera+ earned the company $5.1 million in revenue since its release in June 2010, according to a blog post on the developer’s website. While the figure is impressive, it also highlights how much more earning potential a popular game has compared to other kinds of apps in both sales and in-app purchases.

For comparison, a top grossing game will typically earn between $2 and $3 million a month in the App Store, but can earn as much as $5 million a month if it has a high profile and strong sales.

Unlike some of the highest grossing titles on iOS, Camera+ is a paid app. Over the past year, the free-to-play model has come to dominate the top grossing iOS charts (at the time of writing, eight out of the top 10 highest grossing iPhone apps were free-to-play) but despite being a paid app, Camera+ does offer a single in-app purchase.

According to TapTapTap, only five percent of Camera+ sales are for its optional analogue effects pack, a figure far lower than Germany’s App Zap reports for in-app purchases in its paid game, Kick the Buddy. According to figures App Zap provided Inside Mobile Apps in December, 30 percent of paid Kick the Buddy users buy every in-app purchase.

With in-app purchases expected to account for 64 percent of the total app market revenue by 2015, the ability of utilities to generate revenue through in-app purchases will be increasingly important. Unfortunately for developers who create non-game apps, utilities do not offer the same easily justifiable in-app purchases that games can, where users can purchase in-game currency or additional content.

Since its release Camera+ has racked up six million sales, with five million of them in the past 12 months alone, good enough to make the photo editing tool the top-selling non-game app in the App Store in 2011.