difference between union and left join code example

Example 1: difference between join vs union

JOIN combines the ROWs, we will have longer rows at the end. 
We are joining the rows from two or more related tables.

UNION combines the COLUMNs, we will have longer columns at the end.
UNION combine two different query.
We are joining the columns from two or more related tables.
Can be non related tables but queries must select same column names
with same data type.

Example 2: join vs union

JOIN combines the ROWs, we will have longer rows at the end. 
We are joining the rows from two or more related tables.

UNION combines the COLUMNs, we will have longer columns at the end.
UNION combine two different query.
We are joining the columns from two or more related tables.
Can be non related tables but queries must select same
column names with same data type.