우선 NUMs 라는 테이블를 비교를 위해서 만드셔야 합니다

Primary Key 를 꼭 생성 해주시고요

declare @num1 varchar(100),
           @num2 varchar(100)
   
    set @num1 = '1111112323111111232311111123231111912323111111232311111123231111112323111111232311111123231111112323'
    set @num2 = '1111112324111111232415111123241111112324111111232411111123241111112324111111232411111123241111112324'
  

  
   select @num1 as col1,@num2 as col2,COUNT(ELEMENT1) as 틀린수
   from
   (SELECT ROW_NUMBER() OVER(ORDER BY ID ASC) AS ROWNUM1,substring (@num1, ID, 1) AS 'ELEMENT1'
   FROM   NUMS
   WHERE  ID <= LEN(@num1) AND SUBSTRING ( @num1,ID,1) <> '' ) as a
  
   inner join
     
   (SELECT ROW_NUMBER() OVER(ORDER BY ID ASC) AS ROWNUM2,substring (@num2, ID, 1) AS 'ELEMENT2'
   FROM   NUMS
   WHERE  ID <= LEN(@num2) AND SUBSTRING ( @num2,ID,1) <> '' ) as b
   on   ROWNUM1 = ROWNUM2 and ELEMENT1 <> ELEMENT2