what is difference between wmsys.wm_concat and ListAgg

This thread is to discussion what is difference between wmsys.wm_concat and ListAgg for 11G r2. 

*************************************************************************
difference1 

wmsys.wm_concat allows distinct option.
ListAgg does not allows it.

create table diffT(sortKey,Val) as
select 1,'aa' from dual union all
select 2,'bb' from dual union all
select 3,'aa' from dual union all
select 4,'dd' from dual;
 
col concatV for a20
 
select wmsys.wm_concat(distinct Val) as concatV from diffT;
 
concatV 
--------
aa,bb,dd

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difference2 

ListAgg allows to decide string concat order.
wmsys.wm_concat does not allows it.

select ListAgg(Val,',')
       within group(order by sortKey desc) as concatV
from diffT;
 
CONCATV
------------
dd,aa,bb,aa 

*************************************************************************
difference3 

ListAgg allows to decide delimiter.
wmsys.wm_concat does not allows it.

select ListAgg(Val,'***')
       within group(order by sortKey desc) as concatV
from diffT;
 
CONCATV
-----------------
dd***aa***bb***aa

*************************************************************************
difference4 

wmsys.wm_concat allows to be used OLAP function with order by
ListAgg does not allows it.
ListAgg allows only OLAP function without order by.

select sortKey,wmsys.wm_concat(Val)
               over(order by sortKey) as concatV
  from diffT;
 
SORTKEY  CONCATV
-------  -----------
      1  aa
      2  aa,bb
      3  aa,bb,aa
      4  aa,bb,aa,dd

*************************************************************************
difference5 

wmsys.wm_concat allows to be used KEEP
ListAgg does not allows it.

select wmsys.wm_concat(Val) 
       Keep(Dense_Rank First order by Val) as concatV 
  from diffT;
 
CONCATV
-------
aa,aa

wmsys.wm_concat 將資料列轉行

SELECT   code, wmsys.wm_concat (col1) combine
          FROM table
      GROUP BY  code