The error message is telling you exactly what the problem is.

In the first query you have 6 columns. In the second query you only have 2 columns. Both queries must have the same number of columns (or literals) with matching data types when you use UNION, UNION ALL, INTERSECT or EXCEPT.

Code reformatted to make it easier to read:

select

SabtHazineID,

SabtHazine.HazineID,

EndUserNAme,

Tedad,

sabtHazineDate,

Describtion

from

dbo.SabtHazine

left JOIN dbo.Hazine

ON dbo.Hazine.HazineID = dbo.SabtHazine.HazineID

union all

select

Hazine.HazineName,

Hazine.Mablagh

from

AgencyDB.dbo.Hazine

where

HazineID not in (select HazineID from dbo.Hazine);