okay, so, there’s three factors here, Bodypart, Coverage, and Layering.
Each piece of armor covers a given bodypart, which is obvious and I will not bother to elaborate further.
Coverage is the % chance that piece of armor will intercept a blow. So, that kevlar vest has a much lower % to intercept than the winter survivor suit.
third is layering(which is separate from clothing ‘Layer’), which you can shuffle around with +. Simply put, pieces of armor lower on the list are further ‘out’ and roll to see if they block a hit.
So, with your two things, depending on the layering, it will roll to determine which things intercept a blow. given the high coverage of the winter survivor suit, you basically have a chance to either intercept with just that, or both that and the vest.