I would have to see substantial (if not overwhelming) proof that they aren't identical in both spawn chance and drop chance. Until then I would rely on Occam's Razor.
It wouldn't be so horrible for a dev to just come outright and say what they are though.
Is it possible to hook into AO with a program that could track loot by corpse and upload that data to a SQL database somewhere? You could have fairly reliable data from (potentially) hundreds of people and thousands of raids if it were.