1. Key difference 1: State Management approach - T3 follows a traditional state management approach, where the application state is managed through actions, reducers, and selectors. On the other hand, redux-query is a more declarative approach to state management, where the application state is managed through queries and mutations.
2. Key difference 2: Data fetching and caching - T3 does not provide built-in support for data fetching and caching. Developers have to handle data fetching using middleware or libraries such as axios. In contrast, redux-query provides a comprehensive data fetching and caching system out of the box, making it easier to handle complex data fetching scenarios.
3. Key difference 3: Normalization - T3 does not perform data normalization by default. Developers have to manually normalize the data fetched from the server to ensure consistency and efficient updates. However, redux-query automatically normalizes the fetched data, reducing redundancy and improving performance when updating the state.
4. Key difference 4: Configuration and setup - T3 requires developers to set up action types, reducers, and selectors manually, which can be time-consuming and error-prone. On the other hand, redux-query simplifies the configuration and setup process by providing a clear and concise API for defining queries, mutations, and selectors.
5. Key difference 5: Error handling - T3 requires developers to manually handle errors and update the state accordingly. In contrast, redux-query provides built-in error handling mechanisms, making it easier to handle error scenarios and update the state accordingly.
6. Key difference 6: Integration with Redux ecosystem - T3 integrates seamlessly with the Redux ecosystem, allowing developers to leverage existing Redux middleware, tools, and extensions. On the other hand, redux-query provides its own middleware and extensions, offering a more specialized and focused approach to state management.

In summary, T3 and redux-query differ in their state management approach, data fetching and caching capabilities, normalization support, configuration and setup process, error handling mechanisms, and integration with the Redux ecosystem.