Variation is seen as a value of Android products, said Christy Wyatt, corporate vice president at Motorola Mobility, at the AnDevCon Android developer conference in San Mateo, Calif. Some customers, for example, love the features Motorola puts in the Droid smartphone family. But she acknowledged developer concerns. "Managing differentiation against fragmentation is kind of a delicate balance," Wyatt said.

An example of differentiation developers face in Motorola Mobility's systems involves the and Atrix 4G. Released within a week of each other early this year, the systems use different interfaces for common features such as setting up email.

Testing and certification programs do a good job of keeping APIs and implementations consistent, Wyatt said. Except for Google Experience Devices, such as the Xoom, Motorola's devices launched beginning late last year have the same baseline of features, but there are some UI changes and customization from telecommunications operators, Wyatt said. She encouraged developers to test applications across devices, although she added Android is "smarter" about rendering on different screens.

A developer at AnDevCon acknowledged differentiation in Android systems. "Different device manufacturers are modifying the Android operating system to their liking," making such changes as modifying the UI, said Marek Szany, developer with Eset, in Slovakia. Android itself features version 2.4, for mobile devices, and , he said. "We have to deal [with fragmentation]. We have no choice," he said. Eset develops security applications for Android systems, Szany said.