What's the difference between a "Surface Modifier" and an "additive"?

re: a product called Fastex
www.FastexFX1.com

Thanx,
Wally

Perhaps you can tell us.

It both significantly reduces friction and improves the anti-wear characteristics of metal surfaces. This modified surface has a much higher shear strength to protect equipment and improve the operating performance. It protects against thermal damage traditionally caused by extreme loading pressures, oil film breakdown or lubricant failure by providing a low friction and good anti-wear barrier between metal surfaces.

I think their "surface modifiers" are the same thing listed as an additive package by other vendors. ie: R&O, VI improvers, EP, Moly additive,etc.
They say that the surface of the oil is modified for these abilities, but what they don't say is they have modified it with additives if it has a base oil, and chemically modified it if it is a synethetic.
Dave