Environment Masks - High-Tech vs Ultra-Tech

[Kallatari]

A quick question: why is it that the High-Tech sealed environmental masks/helmets tend to have No Sense of Taste/Smell, while the Ultra-Tech version instead have Protected Smell?

Presumably, the No Sense of Taste/Smell means that odors simply do not go through the helmet, thus the wearer cannot smell anything, and it thereby effectively immune to anything that is delivered by smell (or taste). To me, that makes sense. Why is it that suddenly in the ultra-tech helmets that odors can now go through these apparently sealed helmets (such as the various space helmets), and the wearer instead merely receives a +5 bonus to resist attacks based on smell?

I have a similar question as to why some helmets have Immunity to Eye and Nose Irritants, but not others. I would assume any sealed helmet/outfit would provide that benefit? Again, the distinction appears to be mostly High-Tech vs Ultra-Tech, but even some of the helmets in High-Tech do not have this feature.