Reverb Range/ DIffusor

[Sequence2]

Hey guys
Wanted to ask about the Reverb effect unit on Zebra2
I am having troubles understanding exactly what the Range knob is doing when I increase the value for both the reverb section and the diffusor section.. (It says delay times from extremely short to rather long.. but what does it mean by 'delay times'?

My second question is how does the Diffusor sections differ from the reverb section?? (As in, when I turn the D-range knob, what am I changing as opposed to the 'Range' knob above it??)
I understand what a diffuse environment is vs a non-diffuse environment.. so what exactly are each individual controls doing in the diffuse section as opposed to what they would be doing in the reverb section? Should I choose to only use the knobs in either or section?

Any feedback is much appreciated!