Have you worked with non-relational databases? What is the difference from relational ones?

Yes, I have worked with non-relational databases such as MongoDB and Redis. The main difference from relational databases is that non-relational databases do not use fixed schema tables and SQL queries. They are more flexible in data storage, often supporting documents, key-value, graphs, or columns, which allows for better scalability and handling of unstructured data. For example, MongoDB stores data in BSON document format, which is convenient for dynamic and nested structures, and Redis is a fast in-memory key-value store, often used for caching and queues.