distinct and distinctrow difference?

[Tom]

What is the difference between distinct and
distinctrow in SQL?

 

[Allen Browne]

DISTINCT de-duplicates the query results based on only the fields you return
(i.e. those in the SELECT clause.) For example:
SELECT DISTINCT City FROM tblClient;
returns each city just one, regardless of how many clients are in each city.

DISTINCTROW de-duplicates based on ALL the fields. If your table has a
primary key, and the query is based on just this one table, then DISTINCTROW
makes no difference, since the primary key guarantees uniqueness.

Well, that's how it's supposed to work anyway.
In practice, Access gets DISTINCT wrong sometimes:
http://allenbrowne.com/bug-12.html