Cube.js and Metabase are both powerful business intelligence tools with their own unique features and capabilities. However, there are several key differences between the two that differentiate their functionality and use cases.

1. Data Exploration and Visualization: Cube.js focuses on providing a comprehensive data exploration and visualization framework that enables businesses to create interactive dashboards and reports. It offers advanced features such as drill-down, filtering, and grouping, allowing users to analyze and visualize data from multiple sources in real-time. On the other hand, Metabase primarily focuses on data visualization and reporting, providing a user-friendly interface for users to create and share visualizations without the need for SQL knowledge.

2. Customizable Query Generation: Cube.js allows users to generate complex SQL queries on the fly, providing flexibility and control over the data retrieval process. It features granular control over the query generation process, enabling users to optimize performance and create advanced calculations and aggregations. In contrast, Metabase relies on a simple query builder interface and doesn't offer the same level of customizability and control over the query generation process as Cube.js.

3. Real-time Processing and Streaming: Cube.js is designed to handle real-time data processing and streaming scenarios, making it well-suited for applications that require up-to-date insights and live data visualization. It supports streaming data sources and can refresh dashboards and reports in real-time. In comparison, Metabase is primarily focused on batch processing and doesn't offer the same level of real-time capabilities as Cube.js.

4. Embeddable Analytics: Cube.js provides a robust set of embedding capabilities, allowing businesses to seamlessly integrate analytics into their applications or websites. It offers SDKs and APIs for embedding dashboards, charts, and reports into custom applications or portals. On the other hand, while Metabase does offer some embedding options, it doesn't provide the same level of flexibility and customization as Cube.js.

5. Complex Data Modeling and Schema Design: Cube.js supports complex data modeling and schema design, allowing users to define relationships between multiple data sources and create hierarchies for drill-down analysis. It provides a flexible and extensible data modeling layer that enables users to define advanced calculations, derived measures, and dimensions. In contrast, Metabase has a simpler data model and doesn't offer the same level of complexity and flexibility in data modeling as Cube.js.

6. Enterprise-Grade Security and Scalability: Cube.js is designed to be scalable and can handle high volumes of data and concurrent users. It provides enterprise-grade security features such as RBAC and LDAP integration for user authentication and authorization. Additionally, it supports data-level security and row-level security for fine-grained access control. While Metabase also offers security features, Cube.js provides more advanced security capabilities and is better suited for enterprise-level deployments.

In Summary, Cube.js offers advanced data exploration and visualization capabilities, customizable query generation, real-time processing, embeddable analytics, complex data modeling, and enterprise-grade security and scalability. Metabase, on the other hand, focuses on providing a user-friendly interface for data visualization and reporting without the same level of advanced functionality and customization options as Cube.js.