The Model-View-Controller (MVC) and Model-View-ViewModel (MVVM) patterns are both architectural design patterns used in Swift and other software development. They aim to separate concerns within an application, but they differ in their approach and benefits.

MVC divides an application into three main components: Model, View, and Controller. The Model represents the data and business logic, the View displays the data to the user, and the Controller manages user interactions and acts as an intermediary between the Model and View. While MVC is straightforward, it can lead to tightly coupled code, making maintenance and testing challenging.

On the other hand, MVVM also separates the application into three parts: Model, View, and ViewModel. The key distinction lies in the ViewModel, which exposes data and commands needed by the View. This approach promotes a more decoupled and testable codebase. The View binds directly to properties and commands in the ViewModel, reducing the need for direct interaction between View and Model. This enhances code maintainability and testability.

MVVM also supports data binding, where changes in the ViewModel automatically update the View. This helps in keeping the user interface in sync with the underlying data. Additionally, the MVVM pattern makes it easier to write unit tests for the ViewModel logic since it can be tested independently of the UI.

In summary, while both MVC and MVVM aim to achieve separation of concerns, MVVM provides better code organization, improved testability, and easier maintenance due to its focus on data-binding and a more isolated ViewModel layer. However, MVVM might introduce some complexity to implement compared to the simpler MVC pattern. The choice between the two depends on the specific requirements and complexity of the project.