Drawing any conclusions about a drive's error reporting based on a few discs is pretty foolish. Comparing scans done in different drives is equally pointless.
It seems we are constanly reminding that what is reported in scans is not on the disc, but occurs in the reading process. Confirm questionable scans with a transfer rate test if you like, but there's no such thing as an "unreliable" scan.
Calling a drive a good or bad reader based on scans is also a serious over-simplification. Only a transfer rate test or Scandisc test can determine a drive's ability or inability to actually read a disc.
Discs that give widely varying results in different tests or different drives are almost always discs of marginal quality that may have a variety of issues. Those issues may or may not be related to actual burn quality. More than likely a combination of issues will come together to make a disc problematic, and again, burn quality is only one of them. Error scans are not reporting burn quality directly, and any of those "issues" can translate to high error rates.
One drive may have an enhanced sensitivity to one of those potential issues, where another does not. This is equally true of 2 drives of the same model, as it is of 2 different models.