Oracle 21c

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
create table your_table (name) as
select 'C:\Dir1\RESULT\filelist\filename.file' from dual union all
select 'C:\Dir1\RESULT\filelist\file2.file' from dual union all
select 'C:\Dir1\RESULT\filelist\file3.file' from dual union all
select 'C:\Dir2\RESULT\filelist\filename.file' from dual union all
select 'C:\Dir2\RESULT\filelist\file2.file' from dual
5 rows affected

SELECT
CASE
  WHEN name LIKE 'C:\Dir1\RESULT\filelist\%'
  THEN REPLACE (UPPER(name),
    'C:\DIR1\RESULT\FILELIST\',
    'E:\SomeOtherDir1\RESULT\x\y\z\filelist\')

  WHEN name LIKE 'C:\Dir2\RESULT\filelist\%'
  THEN REPLACE (UPPER(name), 
    'C:\DIR2\RESULT\FILELIST\',
    'E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\')
-- etc
  END
  || CASE WHEN ROW_NUMBER() OVER (ORDER BY name DESC) > 1 THEN ',' END
  AS new_path
FROM your_table ORDER BY 1;


NEW_PATH


E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILE2.FILE,

E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILE3.FILE,

E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILENAME.FILE,

E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\FILE2.FILE,

E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\FILENAME.FILE


SELECT new_path
  || CASE WHEN ROW_NUMBER() OVER (ORDER BY new_path DESC) > 1 THEN ',' END
  AS new_path
FROM (
  SELECT
  CASE
    WHEN name LIKE 'C:\Dir1\RESULT\filelist\%'
    THEN REPLACE (UPPER(name),
      'C:\DIR1\RESULT\FILELIST\',
      'E:\SomeOtherDir1\RESULT\x\y\z\filelist\')

    WHEN name LIKE 'C:\Dir2\RESULT\filelist\%'
    THEN REPLACE (UPPER(name), 
      'C:\DIR2\RESULT\FILELIST\',
      'E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\')
  -- etc
    END AS new_path
  FROM your_table ORDER BY 1
)
ORDER BY new_path;


NEW_PATH


E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILE2.FILE,

E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILE3.FILE,

E:\SomeOtherDir1\RESULT\x\y\z\filelist\FILENAME.FILE,

E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\FILE2.FILE,

E:\SomeOtherDir2\RESULT\1\2\3\FILELIST\FILENAME.FILE