Internal 3d model

Relationship is actually the state or content of the relationship model at a certain moment. In other words, a relational schema is a type and a relationship is its value. The relationship model is static and stable, while the relationship is dynamic and constantly changing with time, because the relationship operation is constantly updating the data in the database.

But in practice, relational model and relational system are often called relationships, and readers can distinguish them from the context.