In this case? Nothing that I am aware of.

However mil surp supplies can be very limited, so when OP asked about pricing differences, comparing NIB prices from a retailer vs NIB prices on a pair of size 14s for sale from somebody who bought an auction pallet? That can explain some discrepancies in cost.

Plus, Mil Surp often doesn't get the same customer support as retail items. I used to work for a company that sold items retail and to the military. Retail items had full lifetime warranty, items sold to the military did not - they had a different repair/replace contract.