difference between explain plan and execution plan

Question

Can anyone explain me what is the difference between execution plan and explain plan.

When I execute

 set autotrace traceonly;
 select * from emp where empno=7369;

Execution Plan
----------------------------------------------------------
  0       SELECT STATEMENT Optimizer Mode=ALL_ROWS (Cost=1 Card=1 Bytes=38)
  1    0    TABLE ACCESS BY INDEX ROWID SCOTT.EMP (Cost=1 Card=1 Bytes=38)
  2    1      INDEX UNIQUE SCAN SCOTT.PK_EMP (Cost=0 Card=1)


 Explain Plan

 explain plan for select * from emp where empno=7369;
 select * from table(dbms_xplan.display);

Plan hash value: 2949544139

--------------------------------------------------------------------------------------
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |        |     1 |    38 |     1   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    38 |     1   (0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | PK_EMP |     1 |       |     0   (0)| 00:00:01 |
--------------------------------------------------------------------------------------

I am getting the same output, so what is the difference between the two.

Answer 1

The explain plan is what the optimizer thinks will happen when you run, the execution plan is actually happened when you ran the query.

See link here.

http://tkyte.blogspot.co.uk/2007/04/when-explanation-doesn-sound-quite.html