Final answer:
A database schema is the blueprint of the database structure which changes infrequently, whereas a database instance is the actual data stored those changes regularly as the database is updated.
Step-by-step explanation:
Understanding Database Schema and Database Instance:
The terms database schema and database instance are important concepts in the realm of data management and databases. A database schema refers to the formal description of the data structure, including the organization, constraints, and relationships between data elements; essentially the blueprint for how data is organized in a database. This schema tends to change infrequently as it represents the design of the database. On the other hand, a database instance is the actual content of the database at a particular moment in time. It includes the collection of tables, views, and other database objects containing live data that changes every time the database is updated. While the schema is considered the intension or the theoretical design, the instance represents the extension or the concrete data within the framework of that design.
When distinguishing between the two, it's important to remember that changes to the schema affect the structure of the database, whereas changes to the instance refer to modifications of the actual data within the database. This distinction is similar to the difference between a building's architectural plan (schema) and the actual people and furniture within the building at any given moment (instance).