The diffraction alone can not decide. Significantly different "physical" size distributions could describe equally well the peak profile (J.Appl.Cryst. v35 (2002) 338-346 - self citation too). Nicolae Popa
Looking at your figures 6b1 and 6b2, I measure how we differ on the sense of "significantly different". As you comment in the text, "The curves 1 and 2 differ in the position of the maximum by only 2 A and in height of the maximum by 9.76%".
I would not call that "significantly different" but "very similar".
Armel
