A generated GraphQL schema is a machine-readable document that declares available operations and their return types, allowing backend services and clients to have a shared understanding of an API. It can be used to merge data sources from different databases into one schema, providing flexibility to clients in selecting what parts of the data they want to get back. However, using generated schemas has trade-offs, such as not allowing for changes to the types, which may lead to duplication of code and maintenance issues if the underlying database is changed or migrated. Client-oriented schemas, on the other hand, provide flexibility and abstraction, allowing clients to customize their response selections while hiding service implementation details. They can be built with a schema-first or code-only approach and are beneficial for teams that want to ship new features quickly with minimal effort. The choice of using generated or client-oriented schemas depends on the specific needs and goals of the project, considering factors such as scalability, maintenance, and client requirements.