Architecture of the Database is designed to depict the functionality of the Database. External level or User View Level shows how data is viewed by an individual user. Conceptual Level shows how data is viewed by a community of users and the Internal Level shows how data is physically stored. They are based on schemas.
Basically data base are designed using three tier architecture. Each have its own functionality like physical level deals with query processing on the data and storage of the data. Conceptual level deals with software program which is responsible for managing the data and provide interface between user and data base. And upper layer i.e. User view layer provide functionality of operation performed on the data by various users.