1. Programming Model: One key difference between Micronaut Framework and Ratpack is their programming model. Micronaut follows a traditional model that emphasizes compile-time type checking and reflection-free API, while Ratpack is more aligned with a reactive programming model, leveraging the power of non-blocking I/O.

2. Configuration Management: Another significant difference is in the area of configuration management. Micronaut uses a type-safe configuration system that is designed to catch errors at compile time, thus providing a more robust and reliable configuration mechanism. On the other hand, Ratpack relies on a more conventional configuration approach with properties files or external configurations.

3. Dependency Injection: Micronaut uses a compile-time annotation processor to generate all the necessary machinery for dependency injection, resulting in faster startup times and reduced memory consumption. In contrast, Ratpack relies on Guice for dependency injection, which offers a more flexible but slightly slower initialization process.

4. Performance: In terms of performance, Micronaut is known for its impressive startup time and low memory footprint, making it a suitable choice for microservices and serverless applications. Ratpack, while also performant, may not be as lightweight or efficient as Micronaut in certain use cases due to its reliance on the JVM’s event loop.

5. Tooling and Ecosystem: Micronaut has a vibrant ecosystem and strong support from the community, with a rich set of libraries and integrations available. On the other hand, Ratpack, although backed by a dedicated team, may not have the same level of community contribution and tooling support as Micronaut.

In Summary, Micronaut and Ratpack differ in their programming model, configuration management, dependency injection mechanism, performance characteristics, and ecosystem support.