Entity: An entity is an object or concept that can have data stored about it. Entities are typically nouns and represent real-world objects or things, such as "Person," "Book," or "Employee." Each entity is uniquely identifiable, and it is often associated with attributes that describe its properties.

Relationship: A relationship defines how two or more entities are connected to each other. For example, in a database schema, relationships represent the associations between tables, such as "an employee works for a department" or "a customer places an order."