What on earth is diffusion chorus? As the name implies, it has diffusion (sort of a red-headed step-child of reverb) and modulating delays (which, as we all know, equals "chorus"). Vapor takes this underused effect, usually only available in high-end hardware boxes, and makes it available to anyone.
Vapor's main purpose is to add top-end shimmer to pads, strings, and rhythm guitar to make those sounds cut through the mix. However, at more extreme settings, unique modulation effects can easily be attained.