What is the difference between Union and Join?

Answer 1

UNION combines the results of two or more queries into a single result se. JOINs you can retrieve the data from two or more tables based on logical relationship between the tables.

Answer 2

if tables are joined one above other it is union
if tables are joined side by side it is join

Answer 3

'union' selects the same type of data (the same columns) from more than one table - like adding the next table to the bottom of the previous one;
'join' selects different type of data (different columns) from more than one table - like adding more columns next to the first table.

Answer 4

What many SoloLearn users are doing is searching "join vs union" on the Internet and posting that as part of their answer. I am going to respect authors or bloggers response and I am going to provide you two links that is going to take you to the concepts and examples, step-by-step in what is a "join" and what is an "union". At the end you will have your own understanding and conclusion what is a join vs union.

http://www.w3schools.com/sql/sql_join.asp

http://www.w3schools.com/sql/sql_union.asp