Is Nano a new product class?

No, nano is not a new product class, it simply describes an order of magnitude (see also the question “What does nano actually mean?”). If a product has the prefix “nano-”, this means that it contains particles in the nano range or that it has been processed and improved using nanotechnology.
The prefix “nano-” is frequently used for products that exhibit improved properties as a result of nanotechnology. These include, to name only a few examples, improved surface properties (such as “dirt-repellent”, “water-repellent”, “scratch resistant”, “fire-resistant”, “self cleaning”, “heat-insulating”, “easy to clean”), greater weather resistance, and improved color characteristics.
Synthetic amorphous silica (SAS), in contrast, has been produced in basically unchanged form for many decades.