What are the main differences between using ActiveRecord and the principles of Clean Architecture when designing a system?

ActiveRecord is a pattern where the model object directly handles data access and business logic, combining them in a single class. This simplifies working with the database but can lead to tight coupling and difficulty in scaling.

Clean Architecture separates the system into layers with clear boundaries:

• Entities — business logic and rules.
• Use Cases — applications and usage scenarios.
• Interfaces and infrastructure — interaction with external systems, including the database.

In Clean Architecture, the model should not directly know about the database; data access is implemented through interfaces and repositories, which increases testability and flexibility.

Thus, ActiveRecord combines data and logic in one class, while Clean Architecture separates responsibilities, improving system maintainability and scalability.