요청하신 케이스가 전부인가요? (A 에만 자료가 있는 경우)
혹시 B 에만 자료가 있는 경우가 존재할 가능성은 없는지요?

WITH tbl_a AS
(
SELECT '2023-11-04' rundatetime, '홍길동' name, '1' desc_
UNION ALL SELECT '2023-11-04', '홍길순', '2'
UNION ALL SELECT '2023-11-04', '김길동', '3'
UNION ALL SELECT '2023-11-05', '홍길동', '11'
UNION ALL SELECT '2023-11-05', '홍길순', '22'
UNION ALL SELECT '2023-11-05', '김길동', '33'
UNION ALL SELECT '2023-11-06', '홍길동', '111'
UNION ALL SELECT '2023-11-06', '홍길순', '222'
UNION ALL SELECT '2023-11-06', '김길동', '333'
)
, tbl_b AS
(
SELECT '2023-11-04' rundatetime, '강일이' name, '4' desc_
UNION ALL SELECT '2023-11-04', '이이삼', '5'
UNION ALL SELECT '2023-11-06', '강일이', '444'
UNION ALL SELECT '2023-11-06', '이이삼', '555'
)
SELECT *
  FROM tbl_a
 WHERE rundatetime IN (SELECT rundatetime FROM tbl_b)
 UNION ALL
SELECT *
  FROM tbl_b
 ORDER BY 1, 3
;