There are a few things going on here that could cause this and there is possibly an interaction of variables that makes the explanation harder.
First, BenQ scans the PIF errors with a different count than Liteon, so you cannot compare them directly. BenQ will show error levels 8X higher. This is normal.
Second, any scan is a measure of a drive's ability to read. The BenQ burner is generally considered to be much better than Liteon. As well, the BenQ has a reputation for being a very good reader. Differnt drives will just read different media with different results.
Also BenQ owners scan at 8X whereas Liteon owners scan at 4X. If you want to look at the variabilities of speed and reading, run CDSpeed's quick scan and get ready to choke. :Z
With these factors, it is not at all out of line to see your results. Most people would go with the Liteon Kprobe scans at 4X as the most reliable, especially when you are being very discriminating.