Terminology

Schema

A GraphQL schema is an artifact describing the API provided by a given GraphQL endpoint. This is likely to contain a set of Queries, Mutations and Subscriptions, and a description of the Objects which they return.

Subgraph Schema

A Subgraph is the Schema of an individual service. These may be stitched together to form a Supergraph.

Supergraph Schema

A Supergraph is simply a GraphQL Schema which has been stitched together from various Subgraphs.