Both gases are chemically inert, taste and odorless, inflammable and of course non toxic, so perfectly apt to create a protective atmosphere to protect your wines from oxidation. Argon is significantly heavier than air (and than nitrogen the main component of air), so it covers the wine like a heavy carpet from oxidation. However since the bottles are kept under a light, constant overpressure in our dispensers, nitrogen is just as apt to avoid air from entering into the bottle as argon. It can be that the preservation effect of argon is slightly stronger, but both gases allow for min. 14 days of preservation. Food grade gasiform nitrogen is slightly cheaper than argon. Some clients experience the effect that small quantities of argon are also dispensed with the wine into the glass although perfectly harm and tasteless it may cover up the first expression of aromas, which is an argument to use nitrogen instead especially for tasting situations.
