The JOIN operator is used to combine rows from two or more tables based on a specified condition. The UNION operator is used to combine the results sets of two or more queries.
The main difference between these two operators is that JOIN combines rows from two tables that have common values in one or more columns, while UNION combines rows from two tables that do not have common values.
For example, the JOIN operator can be used to combine the tables employees and departments to get a list of all employees and their departments. The UNION operator can be used to combine the tables sales and expenses to get a list of all sales and expenses.
