Difference between JOIN and UNION in SQL

Pre-requisites: JOIN, UNION

JOIN in SQL is used to combine data from many tables based on a matched condition between them. The data combined using the JOIN statement results in new columns. Consider the two tables:

Boys

Girls

Example:

sql> SELECT Boys.Name, Boys.Age, Girls.Address,
     FROM Boys INNER JOIN Girls 
     ON Boys.Rollno = Girls.Rollno; 

The resultant table is: 

UNION in SQL is used to combine the result set of two or more SELECT statements. The data combined using the UNION statement is into results into new distinct rows. 

Example:

sql> SELECT Name FROM Boys 
     WHERE Rollno < 16 
     UNION
     SELECT Name FROM Girls 
     WHERE Rollno > 9 

Output:

Difference between JOIN and UNION in SQL