Hi Tim,
Can you describe a bit more about how they are different (perhaps with screenshots)?
When we get questions like this it often has to do with the difference between Preview and Run in the web app.
To make it easier to quickly iterate on a query, Dremio works with a sampling of the data by default:
To see the results from the complete set of data, you can choose to Run your query:
Downloads always do a full Run (though are limited to the first million results).