Best way to order records when using union/unioun all

select id,name,address,'id1' orderkey from test1
union all
select id,name,address,'id2' orderkey from test3
order by orderkey,address;

select * from 
(select id,name,address,1'sortby' from test1
union all
select id,name,address,2'sortby' from test3) t
order by sortby,address;