What is the difference between getting information via Access and MS Query?

[almostanexpert]

I have been trying to extract the same data set via an ODBC connection to a main frame database. One attempt has been using Access simply Query and the other via MS Query. The Access simple query does not return the information I need yet MS Query does. How can there be a difference if I am using the same parameters on both queries? Can someone explain this?

Thanks.