Apple and Nokia lead the way when it comes to churning through distinct applications in both its top 10 and top 300 apps.

A new study of various mobile application stores during the month of April conducted by research company Distimo found that the top apps chart on Google's Android Market had considerably less turnover than the one on Apple's App Store for the iPhone, which leads to less downloads overall.

In terms of numbers, that works out to 94 unique applications in the App Store for the iPhone's top 10 free and paid categories during the month of April, with just 26 in the Android Market during the same time period. For the top 300 apps in the iPhone's App Store, the company found there were 843 unique free applications and 584 unique paid applications. That's compared to Android Market's 388 free apps, and 363 top paid apps that made up the top 300 paid and free lists for that platform.

"The fact that many applications have been downloaded relatively few times may be at least partially due to the fact that the top charts in the Google Android Market change very little over time," the report said. "This is caused by the fact that Google also takes long-term performance of applications into account in order to rank applications."

However, that difference could be short-lived, based on changes made to the way both Apple and Google have begun ranking applications as part of these top charts.

"Google recently made major changes to the Web storefront of the Google Android Market," the report said. "It now displays more local content and top new and trending charts. Perhaps these, and future changes, will provide a higher probability for success for a larger proportion of the applications in the Google Android Market."

Evidence from early April, which Distimo's report covers, points to Apple rolling out its own changes to App Store rankings based on app chart movements across the board. Those changes were said to add weight to rankings within individual categories to affect an app's overall ranking.

Some other interesting findings from Distimo's report include Google Maps being the most-downloaded app on the Android Market, at more than 50 million downloads. To put that in perspective, just 96 applications on the Android Market have hit download numbers higher than 5 million. Distimo also found that 20 percent of free applications, and 80 percent of all paid applications on the Android Market have been downloaded less than 100 times since the store opened.

Google's Android Market inventory is now up to 200,000 free and paid applications, according to Google's latest numbers. Apple's most recently announced numbers put it north of 350,000 apps. An estimate posted earlier his week pegged Apple's App Store at reaching 500,000 apps.