A schema is a collection of logical structures of data, or schema objects. A schema is owned by database user and has the same name as that user. Each User owns a single schema. Schema objects can be created and manipulated with SQL and include the following types of objects: Clusters; Database links; Database triggers; Dimensions; External procedure libraries; Indexes and index types; Java classes, Java resources, and Java sources; Materialized views and materialized view logs; Object tables, object types, and object views; Operators; Sequences; Stored functions, procedures, and packages; Synonyms; Tables and index-organized tables; Views;
Other types of objects are also stored in the database and can be created and manipulated with SQL but are not contained in a schema: Contexts; Directories; Profiles; Roles; Tablespaces; Users;
Schema objects are logical data storage structures. Schema objects do not have a one-to-one correspondence to physical files on disk that store their information. however, Oracle stores a schema object logically within a tablespace of the database. The data of each object is physically contained one or more of the tablespace's datafiles. For some objects, such as tables, indexes, and clusters, you can specify how much disk space Oracle allocates for the object within the tablespace's datafiles.
There is no relationship between schemas and tablespaces: a tablespace can contain objects from different schemas, and the objects for a schema can be contained in different tablespaces.