I'm trying to understand the difference between the vias and plated through-holes in these reference Gerber files. On layer 3, I don't understand why there are so many holes (vias)?.
Why are some holes on layer 3 and the NC drill not on the other layers?
And the other holes in the NC drill that don't appear on any of the other layers, what are they? Vias? (I can see them in the final render.)