Code:
SQL> analyze table emp compute statistics;

Table analyzed.

SQL> set autotrace traceonly exp stat
SQL> select count(*) from emp;


Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1)
   1    0   SORT (AGGREGATE)
   2    1     INDEX (FULL SCAN) OF 'EMP_PK' (UNIQUE) (Cost=1 Card=14)




Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          1  consistent gets
          0  physical reads
          0  redo size
        379  bytes sent via SQL*Net to client
        499  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

SQL> select count(1) from emp;


Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1)
   1    0   SORT (AGGREGATE)
   2    1     INDEX (FULL SCAN) OF 'EMP_PK' (UNIQUE) (Cost=1 Card=14)




Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          1  consistent gets
          0  physical reads
          0  redo size
        379  bytes sent via SQL*Net to client
        499  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed
no diffrence