Unless there is some commonality between the data tables then this will not work and does not make sense, you are better off showing two tables one after another.
If there is commonalty you can use :
select c1 as 'x',c2 as 'y' from table1
union
select d1 as 'x', d2 as 'y' from table2
where c1, c2 are the column names from table1 and d1 and d2 from table2, 'x' and 'y' is the name for the columns in your query.