Is DISTINCTROW in MS-Access the same as selecting all the fields and doing a group by on all of them?
Taken from the MSDN page:


  Omits data based on entire duplicate records, not just duplicate fields. For example, you could create a query that joins the Customers and Orders tables on the CustomerID field. The Customers table contains no duplicate CustomerID fields, but the Orders table does because each customer can have many orders. The following SQL statement shows how you can use DISTINCTROW to produce a list of companies that have at least one order but without any details about those orders:

SELECT DISTINCTROW CompanyName
FROM Customers INNER JOIN Orders
ON Customers.CustomerID = Orders.CustomerID
ORDER BY CompanyName;

  
  If you omit DISTINCTROW, this query produces multiple rows for each company that has more than one order.
  
  DISTINCTROW has an effect only when you select fields from some, but not all, of the tables used in the query. DISTINCTROW is ignored if your query includes only one table, or if you output fields from all tables.


To answer your question, is it the same as a GROUP BY on all columns?  No.

By the way, that was the very first link returned from a search for microsoft access distinctrow site:msdn.microsoft.com