How does the physical level of an ER diagram differ from the logical one?

The logical level of an ER diagram describes entities, their attributes, and relationships between them from the perspective of the subject area, without being tied to a specific implementation. It focuses on data structure and business rules.

The physical level reflects how this model will be implemented in a specific DBMS: data types, indexes, tables, constraints, storage details.

Example:

• Logical level: entity "User" with attributes "Name", "Email".
• Physical level: table users with VARCHAR(100) for name, VARCHAR(255) for email, an index on email for quick search.