1. Declarative State Management: Recoiljs allows you to manage the state of your application in a declarative way, where you define the state and the relationships between different parts of the state using plain JavaScript functions. On the other hand, redux-saga is a middleware library for Redux that enables you to handle asynchronous actions using generator functions.
2. Mutable vs Immutable: In Recoiljs, the state is mutable, meaning you can directly mutate the state values. This allows for a more flexible and efficient state update process. Redux-saga, on the other hand, encourages the use of immutable data structures to update the state, which helps to ensure data consistency and avoid side effects.
3. Flexibility in Side Effects: Redux-saga provides a way to handle side effects, such as asynchronous API calls and complex asynchronous flows, in a more granular and explicit manner. It allows you to separate the side effect logic from the action creators and reducers. Recoiljs, on the other hand, doesn't have built-in support for handling side effects and encourages the use of libraries like Redux Thunk or Redux Saga for side effect management.
4. Integration with Redux: Redux-saga is specifically designed to work with Redux and complements it by providing a more advanced and complex way of managing side effects. Recoiljs, on the other hand, is a standalone state management library that doesn't have any dependency on Redux. It can be used as a replacement for Redux or alongside it in a hybrid approach.
5. Performance Optimization: Recoiljs provides tools like selectors and memoization to optimize the performance of your application by minimizing unnecessary re-rendering of components. Redux-saga, on the other hand, focuses more on managing asynchronous actions and doesn't provide specific tools for performance optimization.
6. Community and Ecosystem: Redux-saga has a larger and more mature ecosystem with a strong community support that offers a wide range of plugins, middleware, and tools. Recoiljs, being a relatively new library, has a smaller ecosystem and a growing community, although the potential for future growth is high.

In Summary, Recoiljs provides a declarative and mutable approach to state management, while redux-saga offers a way to handle asynchronous actions and side effects using generator functions in a Redux environment with an emphasis on immutability.