Sometimes thickness isn't the only contributor. Fabric design, porosity, coverage and more play roles. Also, with the sock difference, it's reasonable to assume our boots fit slightly different. Then, did we lace our boots the same way? Lots of variables exist.
So far, the Injinjis (very thin sock) have kept my feet warm. This weekend, they'll get seriously tested as the temps are in the single digits (F) and wind chill in the negative numbers. I think they'll work but I've got my SmartWools in the bag just in case.