A long long time ago, when mobile devices were small and j2me was the only one adequate way to write mobile applications, bugs were happy. But then iOS and Android came to a place and everything changed. Applications became more complicated, smarter and got their own business logic. Of course the smarter application became the more attention we need to focus on the support of the software quality and the main instrument that can help us with that is testing.
But what should we test? Usually in mobile development we use 2 kinds of testing: unit-testing and acceptance testing. After your unit tests will pass you'll know that your code is written according to a specification (or not). After acceptance tests will pass you'll know that your product is written according to a specification.
So that is the main difference: unit testing - for code and acceptance testing - for product.
