I recently had a friend ask for help comparing two comma seperated lists in SQL server using a UDF. I started based around the Split UDF I wrote, and continued from there. The simplest and most performant thing I could think of was to use an INNER JOIN to compare the table values of the two lists. Then just compare the counts you get back to make sure they're all the same. Here's the UDF:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION IsCommaListMatch
(
   @list1 varchar(255),
   @list2 varchar(255)
)
RETURNS bit
AS
BEGIN
   DECLARE @isMatch bit

   DECLARE @list1Values TABLE (val int)
   DECLARE @list2Values TABLE (val int)

   INSERT INTO @list1Values SELECT * FROM dbo.Split(@list1)
   INSERT INTO @list2Values SELECT * FROM dbo.Split(@list2)

   DECLARE @count1 int
   DECLARE @count2 int
   DECLARE @count1Join int
   DECLARE @count2Join int

   SELECT @count1=COUNT(val) FROM @list1Values
   SELECT @count2=COUNT(val) FROM @list2Values

   SELECT
      @count1Join=COUNT(list1Values.val),
      @count2Join=COUNT(list2Values.val)
   FROM
      @list1Values list1Values
         INNER JOIN @list2Values list2Values
            ON
               list1Values.val=list2Values.val

   IF @count1=@count2 AND @count1=@count1Join AND @count2=@count2Join
      SET @isMatch=1
   ELSE
      SET @isMatch=0

   RETURN @isMatch
END

GO

As always, feel free to contact me if you have ideas on improving this.