[DATABASE] Difference between intersect and union

I have two relations namely PROPERTY and LEASE, see the PROPERTYNO attributes returned from PROPERTY and LEASE respectively: In intersect, tuples which exists in both relations will be displayed removing duplicates. In union, all tuples from property and all tuples from lease will be displayed removing duplicates:

Link: http://cyruslab.net/2018/11/30/database-difference-between-intersect-and-union/