1. 1. Null Safety: One key difference between Immutables and Jackson is in their approach to null safety. Immutables provides built-in null safety features, allowing developers to specify which attributes should be non-null and automatically generating null-checking code. This helps prevent runtime null pointer exceptions and ensures the correctness of the data. On the other hand, Jackson does not provide native null safety mechanisms, which means developers need to handle null values manually by writing additional code or using third-party libraries.

2. 2. Annotation-based Configuration: Immutables relies heavily on annotations for configuration. It uses meta-annotations like @Value.Immutable to mark a class as immutable and @Value.Parameter to annotate the constructor parameters. These annotations drive code generation and customize the immutability rules. In contrast, Jackson utilizes a mix of annotations, such as @JsonProperty and @JsonCreator, along with explicit configuration through ObjectMapper instances. Jackson allows more fine-grained control over the serialization and deserialization process by providing more configuration options at runtime.

3. 3. Code Generation: Immutables employs a code generation approach to create immutable classes during compilation. It generates efficient and immutable implementations of interfaces or abstract classes based on the annotated source code. This reduces the overhead of runtime reflection and improves performance. On the other hand, Jackson uses runtime introspection and reflection to handle serialization and deserialization. It dynamically discovers object structure during runtime, which can impact performance compared to the code generation approach of Immutables.

4. 4. Support for Mutability: Immutables focuses on immutability by generating immutable classes. It discourages the use of mutability and mutation methods on generated objects. Immutables provides a separate set of builders that allow creating new instances with modified attributes instead of modifying existing instances directly. In contrast, Jackson does not enforce immutability and allows both mutable and immutable classes. It can serialize and deserialize objects regardless of their mutability.

5. 5. Configuration Flexibility: Immutables offers limited runtime configuration options compared to Jackson. Since Immutables generates code during compilation, most of the configuration decisions need to be made during development time. While this approach leads to more predictable behavior, it reduces flexibility for runtime changes. In contrast, Jackson provides extensive runtime configuration options, making it more suitable for scenarios where configuration parameters may vary dynamically.

6. 6. Ecosystem and Integration: Jackson has a larger ecosystem and community support compared to Immutables. Jackson is a widely adopted JSON processing library and integrates with various frameworks and tools. It provides seamless integration with popular Java frameworks like Spring and JAX-RS. Immutables, on the other hand, is more specialized for generating immutable classes and may not have the same level of integration and community support as Jackson.

In summary, Immutables and Jackson differ in their approach to null safety, configuration, code generation, support for mutability, configuration flexibility, and ecosystem/integration. Immutables provides built-in null safety, relies on annotations for configuration, uses code generation, encourages immutability, offers limited runtime configuration options, and may have a smaller ecosystem and integration support compared to Jackson.