conceptual schema versus physical schema

The conceptual schema sometimes called the logical schema is the data model in the DBMS. It describes all the relations that are stored in the database. These relationships could contain information in the form of entities and relationships. For example, entities such as employees and departments could have relationships such as employees working for a department. Each collection of entities and each collection of schema can be described as a relation, leading to the conceptual schema. The process of arriving at a choice of relations and fields for each relation is called conceptual database design.

The physical schema specifies additional storage details. So it describes further how the conceptual schema is stored in the disk. And file organizations used to store the relations and auxilary data structures such as indexes  that speed up data retrieval operations are all part of physical schema.