Oxygen is odorless.... So probably that.
Actually I didn't know the question itself, I had to look up the adjective used here in order to understand, according to Google and then Merriam-Webster dictionary nascent in chemistry implies a reactive or compound prepared in-situ, or freshly obtained from a reaction.
The nascent oxygen then could be obtained by water electrolysis, a nascent smell in the other hand should be indicating that in the progress of a reaction an aromatic compound (good or bad smell) is obtained.
However as indicated in the answer Oxygen is an odorless gas, so that is the difference.