Essentially , the depth controls how much the oscillator modulates your signal, and the intensity can be looked as a dry/wet mix knob. However the functions are different in the Tremolo pan settings.
So even if depth is 0 , there is still some some effect in the output (except tremolo) , but if intensity is 0 you would get a complete dry signal at the output.The manual explains these knob functions on every algortihm so that should make things more clear.
Hope this helps.
