Discrepancies in score from app to website

I downloaded this to test my hard disks. In the description it was advertised that I could test the write speed of primary or selected storage device. But I couldnt figure out how to tell it to test the speed of my other storage device. All it could test was the primary storage device, i.e. the Macintosh HD. Also I just tested my new iMac 27" with core i7 processor and uploaded the result to their website. On the website they show Verified NovaBench score" which is lower than the NovaBench score displayed in the app. What is the explanation for this?

yashrg about Novabench