A lot of Expo and React Native code can be reused across multiple native platforms, but there are some differences you should be aware of. Native components may look different because of the platform-provided design guidelines. On iOS, Apple implemented their Human Interface guidelines while Android provides their Material Design guidelines. Some of the core components might look different on other platforms because of this.

Let’s take a look at the <Button> component. In this image, you can see how this is rendered on both Android and iOS.

There are also differences in the functionality provided by each platform. Apple wants app developers to use their “Authenticate with Apple” feature, but this is not available on Android. Because of that, it isn’t always possible to provide a unified API for native functionality.