There's absolutely no difference; those are both completely informal terms. A "varnish" (or whatever, there are thousands of names for these thing) is nothing more than a transparent paint base without pigment added. The point was that the claim was made in the article that this is more durable than paint, when AFAICT the only way to make it so it to put a paint(-like coating) on top of the surface anyway. So how is it more durable? Scratch the coating and you scratch off the fancy micro-texture.

It could for instance be more durable because it doesn't fade due to ultra-violet light breaking down the pigment.

The same is true of ionic pigments, though. Only the organics fade in sunlight. Again, hardly an earth-shattering innovation. Might make it useful in toys where toxic pigments can't be used...

How about a micro-coating. Not applied like paint, deposited on the surface like an integrated circuit layer, microns thick. SUre you can still call it paint, you can call the layers of an integrated circuit paint but its deposited differently, is a differnt industrial process, mechanically different, different thermal characteristics, lots of things. More significant in my original comment was this: the color can be "dialed", kind of like "digital color". Paint is imperfectly mixed material with wide color/reflectivity variation over a surface. This new method of coloring a surface is uniform. Imagine the efficiency of a color filter, absorbtive surface, radiative surface etc if the optical properties could be tightly controlled over a wide area.