SQL & PL/SQL

Hello  suppose the following query

SELECT employee_id, resume,

              DBMS_LOB.SUBSTR (resume, 5, 18)  lob_substr,

              substr(resume, 5, 18)   sub   

FROM employees

WHERE employee_id = 170;

resume is of CLOB datatype

and for employee_id 170 is 'Date of Birth: 1 June 1956 Resigned: 30 September 2000'

the results are:

sub

-----------------------------------------------------------------------------

' of Birth: 1 June '

I understand that.

I cannot understand why  DBMS_LOB.SUBSTR (resume, 5, 18)  gives as a result

'June '

Thank you.

What is the difference?