Whats the difference between 

```
SELECT DISTINCT field1 
  FROM table1 cd  
  JOIN table2 
    ON     cd.Company = table2.Name 
       and table2.Id IN (2728) 

```

and 

```
SELECT DISTINCT field1 
  FROM table1 cd  
  JOIN table2 
    ON cd.Company = table2.Name 
 where table2.Id IN (2728) 

```

both return the same result and both have the same explain output