The ozone irradiated by ultraviolet rays is relatively pure, with only fishy smell, and high-voltage discharge will also produce nitrogen oxides, such as NO 1, NO2, etc.

The specific process of nitrogen oxide formation is that nitrogen generates NO 1 under high voltage discharge, and NO 1 reacts with O2 to generate NO2.

This is the main reason for the different smells. Of course, there are other reactions, but they have little to do with the smell, so I won't introduce them here.