1. Development Language: Create React Native App utilizes JavaScript and React to develop mobile applications, while RubyMotion uses the Ruby programming language. This difference in programming languages can impact the development process and the skillset required for developers.

2. Community and Ecosystem: React Native has a larger and more active community compared to RubyMotion. This means that React Native developers have access to a wider range of resources, libraries, and community support, making it easier to troubleshoot issues and find solutions.

3. Platform Compatibility: Create React Native App allows developers to build cross-platform applications for iOS and Android, enabling code sharing between the two platforms. On the other hand, RubyMotion provides more seamless integration with native iOS and Android APIs, allowing for more fine-tuned customization and optimization for each platform.

4. Ease of Learning Curve: Create React Native App is known for its relatively easy learning curve, especially for developers already familiar with JavaScript and React. RubyMotion, on the other hand, may be more challenging for developers who are new to the Ruby programming language.

5. Cost and Licensing: Create React Native App is an open-source framework, meaning it is free to use and developers have access to its source code. RubyMotion, on the other hand, requires a paid license, which can be a factor to consider for budget-conscious developers or teams.

6. Performance Optimization: RubyMotion offers more control over the performance optimization of mobile applications, allowing developers to fine-tune performance for specific use cases. Create React Native App, while efficient, may not offer the same level of optimization capabilities.

In Summary, the key differences between Create React Native App and RubyMotion lie in the development language, community support, platform compatibility, learning curve, cost, and performance optimization.