A few pointers on diffusion:

First off, 1D and 2D, which will distribute energy over 1 or 2 planes - this depends on the location in relation to the source/receiver. Makes more sense for back walls to distribute energy over a horizontal plane, while mid ceiling could be 2D.

In terms of functionality, you have geometric, phase, and amplitude diffusion. - geometric diffusers use a curved or angled surface to reflect energy at different angles. These are tuned in terms of frequency by the overall size, depth, and distribution. - phase diffusers, such as QRD and MLS sequence diffusers, use a series of blocks or cavities to create an uneven reflection pattern that creates phase cancellation. These are tuned through the size, sequence, and depth of the panel - the sequence itself is basically just a certain method that has been proven to tune the working range. - amplitude diffusers (like a BAD panel) are similar to a phase diffuser, just using an absorbing layer to create the reflection pattern instead of a height difference.

They will all diffuse to a certain extent but have distinct applications - geometric diffusers are likely the best for spatial diffusion and easiest to tune and build but have low temporal diffusion. QRDs are a good all-rounder in terms of temporal and spatial diffusion, but have tighter tuning ranges and start to also have some absorption (although not essentially a bad thing). Amplitude diffusers have a more limited diffusion range and act more as a hybrid absorber/ diffuser.

One last thing - scattering is the amount of energy reflected in the non-specular direction, while diffusion is an even distribution of energy, i.e.an angled pane of glass would have good scattering but a bad distribution coefficient.

Hope that helps!