difference between EXPLAIN PLAN and SET AUTOTRACE TRACEONLY EXPLAIN

most of the time I use set autot trace exp in order to get the execution plan. It seems more easy than explain plan for [query]; followed by select * from table (dbms_xplan.display);.

However, take care, set autotrace traceonly explain does modify the rows if you explain a plan for insert/update/delete.

SQL> set autot trace exp
SQL> delete emp;

14 rows deleted.


Execution Plan
----------------------------------------------------------
Plan hash value: 3538878155

---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | DELETE STATEMENT | | 14 | 98 | 2 (0)| 00:00:01 |
| 1 | DELETE | EMP | | | | |
| 2 | TABLE ACCESS FULL| EMP | 14 | 98 | 2 (0)| 00:00:01 |
---------------------------------------------------------------------------

SQL> set autot off
SQL> select count(*) from emp;
0
SQL> roll
Rollback complete.

but explain plan does not
SQL> select count(*) from emp;
14

SQL> explain plan for delete emp;

Explained.

SQL> select * from table (dbms_xplan.display);
Plan hash value: 3538878155

---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | DELETE STATEMENT | | 14 | 98 | 2 (0)| 00:00:01 |
| 1 | DELETE | EMP | | | | |
| 2 | TABLE ACCESS FULL| EMP | 14 | 98 | 2 (0)| 00:00:01 |
---------------------------------------------------------------------------

SQL> select count(*) from emp;
14