N2O, N₂O, NO2 — same product

You'll see this searched and written several ways: N2O, N₂O, N20 (a common typo, with the letter O mistyped as the number zero), and less accurately NO2. They all refer to the same compound, nitrous oxide — not nitrogen dioxide, which NO2 technically denotes and is a different, unrelated gas. Whichever way you've seen it written, a "cream charger," "whipped cream charger," and "N₂O charger" are the same product.

If you're new to the product itself, start with what a cream charger is, or go straight to how to use one.