Could be both, i suggest the following test:
Scan the same disc with same speed with same software, lets say, 3 times, make an average...
Now do the same with the other software and compare their average values...
That would be interesting so see.
PS. I am 100% sure that there will be % differences between the scans of the same LiteON drive, the question here is how big. That's why i have asked Nicw to add option to be able to scan disc X times and present an average graph of the X scans...