COALESCE function and CASE WHEN

I tried to compare COALESCE and CASE WHEN.



SELECT  SUM(val)
FROM    (
  select CASE
       WHEN 1 IS NULL THEN  LENGTH(RAWTOHEX(SYS_GUID()))
       ELSE  1
       END AS val
  FROM dual
  CONNECT BY level = 10000
  );


There is no difference!