App analytics firm Distimo noted some pronounced discrepancies between the use of app ratings categories in Apple’s App Store and Google’s Android Market, across products available in both.

The company assessed a total of 117 apps available across the platforms, noting that “one could expect that this sample would have a similar distribution of age rating in both stores.” However, the lowest age range (4+ for the App Store, “Everyone” for Android Market) was used by 73 percent of Apple apps compared to 42 percent for the Google platform.

In addition, only 9 percent of iOS developers used the second lowest category (9+), compared with 37 percent for Android Market (“Low Maturity”).

Further up the scale, the differences are less pronounced. While 2 percent of apps were categorised as 17+ by Apple, 1 percent of Android Market titles were in the “High Maturity” category.

Distimo notes that while developers are responsible for rating apps, this is done in line with the relevant store’s guidelines, and there are discrepancies between the two. For example, Android apps which access communications features or location must be rated “Medium Maturity,” whereas Apple does not specify certification levels related to app features.

This means that Twitter and Facebook, for example, are rated in the lowest category for the App Store, but are “Medium Maturity” for Android Market. There are some apps where the differences in ratings are not so clear, however: Distimo noted that Tapmedia’s QR Reader is “Low Maturity” in Android Market, but “17+” in Android Market.