Hi Max,
The main difference is that they relate to different Wazuh components and are used for different purposes.
Wazuh Manager users are related to the Wazuh Server API. They are responsible for performing management operations such as managing agents, retrieving agent information, checking manager status, and accessing other API endpoints. Wazuh API RBAC system is controlled by their permissions. https://documentation.wazuh.com/current/user-manual/manager/index.html
The Wazuh Indexer: users are used to relate to the Wazuh Indexer. They control access to the data stored in the indexer, such as alerts, archives, vulnerabilities, and other indexed information. https://documentation.wazuh.com/current/user-manual/indexer-api/index.html
The Wazuh Dashboard communicates with both services, so it requires credentials for both:
Manager credentials to interact with the Wazuh API.
Indexer credentials to query and display the indexed data.
Let me know if you have any other related queries.