select syntax question

This is what is on postgresql's manual page:

http://www.postgresql.org/idocs/index.php?sql-select.html

SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]
* | expression [ AS output_name ] [, ...]
[ FROM from_item [, ...] ]
[ WHERE condition ]
[ GROUP BY expression [, ...] ]
[ HAVING condition [, ...] ]
[ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]
[ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
[ FOR UPDATE [ OF tablename [, ...] ] ]
[ LIMIT { count | ALL } ]
[ OFFSET start ]

According to this syntax, SELECT DISTINCT COUNT(ID) FROM test
should be valid while SELECT COUNT(DISTINCT ID) FROM test otherwise.

while in fact, both are valid.

Is there any difference between this two queries?

Thanks!

--
Wei Weng
Network Software Engineer
KenCast Inc.