1>A DATA IN A DATABSE IS STORED PHYSICALLY IN A DATAFILE AND LOGICALLY IN A TABLESPACE.

2>A TABLESPACE CAN BELONG TO ONLY ONE DATABASE AT A TIME.

3>A DATABASE CAN CONTAIN MORE THAN ON TABLESPACE.

4>A TABLESPACE CAN CONTAIN ONE OR MORE DATAFLES.

5>A DATAFILE CAN BELONG TO ONLY ONE TABLESPACE AND ONE DATABASE .

Adding on to the above statements

A Tablespace can be associated with one or more DATAFILE ( One - Many )
A DATAFILE can be associated with only one TABLESPACE (One - One ).

Databases tablespaces and datafiles are closely related but they have important differences:

1) An Oracle database consists of at least two logical storage units called tablespaces which collectively store all of the database's data. You must have the SYSTEM and SYSAUX tablespaces and a third tablespace called TEMP is optional.

2) Each tablespace in an Oracle database consists of one or more files called datafiles which are physical structures that conform to the operating system in which Oracle Database is running.

3) A database's data is collectively stored in the datafiles that constitute each tablespace of the database. For example the simplest Oracle database would have one tablespace and one datafile. Another database can have three tablespaces each consisting of two datafiles (for a total of six datafiles).