The difference between MySQL Federated Query and left Association

I define this as a union query, or a query:

1th type: SELECT a.gbname,b.gcontent from Tb_goodsbrand a,tb_goods b WHERE a.gbid = B.gbid

The result is:

#========================================================================

We are using left join to query:

2nd type: SELECT a.gbname,b.gcontent from Tb_goodsbrand a left JOIN tb_goods b on a.gbid = B.gbid

The result is:

Summary: The 1th type is to satisfy all the conditions behind the where, only to show it;

The 2nd kind is the left connection, the left is displayed, the right side has the display, does not have the display.

The difference between MySQL Federated Query and left Association