Something about the field is not a reality, in the first case, so be it.
select t1.*, t2.* from table1 t1 join table2 t2 on t2.field1 = t1.field1 and t2.field2 = t1.field2 and ... -- compare all fields
In the second you subtract:
select t1.* from table1 t1 UNION select t2.* from table2 t2 MINUS select t1.* from table1 t1 join table2 t2 on t2.field1 = t1.field1 and t2.field2 = t1.field2 and ... -- compare all fields