Apple's Core ML 2 vs. Google's ML Kit: What's the difference?

At Apple's Worldwide Developers Conference 2018, the Cupertino company announced Core ML 2, a new version of its machine learning software development kit (SDK) for iOS devices. But it's not the only game in town -- just a few months ago, Google announced ML Kit, a cross-platform AI SDK for both iOS and Android devices. Both toolkits aim to ease the development burden of optimizing large AI models and datasets for mobile apps. So how are they different? Apple's Core ML debuted in June 2017 as a no-frills way for developers to integrate trained machine learning models into their iOS, macOS, and tvOS apps; trained models are loaded into Apple's Xcode development environment and packaged in an app bundle.