Is that claimed weight or actual weight on the AmClassic wheels. If it's claimed they probably left out all the hardware/nuts as well as the rim tape. It's pretty common for companies to leave out stuff like that when they weigh their product. Frame manufacturers do it all the time by leaving out the derailleur hanger, integrated headset cups, seat collar, and anything else (some times even weighing a frame prior to paint). The bottom line is don't worry about it. You have a solid functional wheelset that will most likely be completely trouble free while your friends is made by American Classic so it always has two strikes against it.
It might have alloy nipples too. That makes more difference than you would think.