select *
from Inv_AeX_AC_Identification ai
left join Inv_Serial_Number sn on ai._ResourceGuid = sn._ResourceGuid
where sn.[Serial Number] is not null and sn.[Serial Number] != ai.[Hardware Serial Number]
update Inv_Serial_Number
set [Serial Number] = ai.[Hardware Serial Number]
from Inv_AeX_AC_Identification ai
left join Inv_Serial_Number sn on ai._ResourceGuid = sn._ResourceGuid
where sn.[Serial Number] is not null and sn.[Serial Number] != ai.[Hardware Serial Number]