1. 1. Purpose and Language Support: Bazel is an open-source build tool that focuses on providing fast and reliable builds for large-scale projects. It supports multiple languages including Java, C++, Python, Go, and more. On the other hand, Buck is also an open-source build tool designed for fast and incremental builds. It primarily focuses on Android and iOS development, providing optimized builds for these platforms. Gradle is a build automation tool that aims to be highly flexible and supports a wide range of languages and platforms.

2. 2. Build Configuration: Bazel uses a declarative and statically-typed build language called Starlark, allowing for more precise and deterministic builds. It provides a build graph that is defined in a BUILD file, allowing developers to specify dependencies between targets. Buck, on the other hand, uses a simplified version of the Python language for build configuration. It also defines dependencies using BUILD files but supports a more intuitive and flexible syntax. Gradle uses a Groovy-based DSL (Domain-Specific Language) or Kotlin for build configuration. It offers a more expressive and flexible syntax compared to Bazel and Buck.

3. 3. Build Performance: Bazel has a strong emphasis on build performance and is designed to provide fast and incremental builds. It achieves this by caching build artifacts and using advanced dependency analysis. Buck, being specifically optimized for Android and iOS development, also offers fast and incremental builds. It supports fine-grained build caching and parallelization. Gradle, although it provides good build performance, may not be as fast as Bazel or Buck for larger projects. However, it offers a wide range of features and plugins, making it highly customizable for different build scenarios.

4. 4. Plugin Ecosystem: Bazel has a limited number of plugins and extensions compared to Gradle. Its plugin ecosystem is still developing and may not have the same level of community support as Gradle. However, it provides a strong foundation for building scalable and reproducible builds. Buck also has a smaller plugin ecosystem compared to Gradle but still provides essential features for Android and iOS development. Gradle, being one of the most widely used build tools, has a rich and active plugin ecosystem. It offers a vast range of plugins for different languages, frameworks, and tools, making it highly extensible.

5. 5. Integration and IDE Support: Bazel provides seamless integration with popular IDEs such as IntelliJ IDEA and Visual Studio Code, offering features like code navigation, refactoring, and debugging. It also supports integration with Continuous Integration (CI) systems like Jenkins and Travis CI. Buck provides similar integration with IDEs and CI systems, focusing on Android and iOS development. Gradle, being widely adopted, offers excellent integration with IDEs such as IntelliJ IDEA, Android Studio, and Eclipse. It also provides comprehensive support for CI systems and cloud-based build services.

6. 6. Community and Support: Bazel has a growing and active community but may not have the same level of support as Gradle. It is supported by Google and has a dedicated team working on its development. Buck also has an active community, primarily focusing on Android and iOS development. It is supported by Facebook and has ongoing development efforts. Gradle, being widely adopted and backed by Gradle Inc., has a large and vibrant community. It has extensive documentation, tutorials, and user forums, making it easier to find support and resources.

In Summary, Bazel, Buck, and Gradle are all powerful build tools with their own strengths. Bazel is highly scalable and delivers fast and reproducible builds for large-scale projects. Buck provides optimized builds for Android and iOS development. Gradle offers a flexible and extensible build automation solution with a wide range of language and platform support.