1. Dependency Management: Bazel handles dependency management by using a BUILD file format, where dependencies are explicitly defined, while Buildkite does not have built-in dependency management features.
2. Scaling: Bazel is designed for large scale projects with built-in support for scaling and distributed caching, unlike Buildkite which is more suitable for smaller projects.
3. Language Support: Bazel supports multiple programming languages and platforms out of the box, while Buildkite is more focused on continuous integration and deployment workflows without specific language support.
4. Build Configuration: Bazel uses a declarative configuration approach where the build settings are defined in a clear and concise manner, while Buildkite relies on scripts for build configuration which can be more flexible but also more complex.
5. Integration and Ecosystem: Bazel has a robust ecosystem with integrations for various tools and platforms, offering a wider range of functionalities compared to the more focused Buildkite ecosystem.
6. User Interface: Buildkite provides a user-friendly web interface for managing builds and pipelines, making it easier for non-technical users to interact with the build system, while Bazel primarily relies on command-line interface for interactions.

In Summary, Bazel and Buildkite have key differences in dependency management, scaling, language support, build configuration, integration, and user interface.