>In other words, a JOIN is used to merge together two or more tables into single records. A UNION, on the other hand, is always used to concatenate two or more tables into a single result set. Each JOIN may or may not add records; each UNION always does.
On top of that, let's remark that both parts of a UNION must produce the same columns.
"Once again, we come to the Holiday Season, a deeply religious time that each of us observes, in his own way, by going to the mall of his choice." -- Dave Barry
