How to compare two tables in databases

/*
use DMNDB
SELECT
OBJ.NAME as TableName into #dmndbTables
FROM
SYSOBJECTS OBJ
WHERE
OBJ.TYPE = 'U'
go
use DMNqa
SELECT
OBJ.NAME as TableName into #dmnqaTables
FROM
SYSOBJECTS OBJ
WHERE
OBJ.TYPE = 'U'

*/
go

select TableName AS dmndbTables FROM #dmndbTables WHERE TableName NOT IN (SELECT TableName FROM #dmnqaTables)

select TableName AS dmnQATables FROM #dmnQATables WHERE TableName NOT IN (SELECT TableName FROM #dmnDBTables)

---------------------
--we can get table columns
CREATE VIEW V_ALL_USERTABLE_COLUMNS
AS
(
SELECT
OBJ.NAME as TableName,
COL.NAME as ColName,
TYP.NAME AS TYPE

FROM
SYSOBJECTS OBJ,
SYSCOLUMNS COL,
SYSTYPES TYP

WHERE
OBJ.TYPE = 'U'
AND OBJ.ID = COL.ID
AND COL.TYPE = TYP.TYPE
)

how to get rows into single field

declare @AccountCategory varchar(max)

set @AccountCategory=''
SELECT @AccountCategory=@AccountCategory+', '+ Prefix FROM(select Prefix
from a_AccPrefixIncludes) AS Prefix

print @AccountCategory