Suppose we have 2 circles of unequal radii, A and B, and we do not know which is greater. We have n random points inside each circle, and we have the distance between every pair of points inside the circles.
For example, for 10 random points inside A and 10 random points inside B, we have the distances between the 45 pairs of points in A and 45 pairs of points in B.
How do we determine which circle has the greater radius?
This Wikipedia article shows you how to find the smallest circle enclosing a set of points. The algorithms are not trivial, but the second one (Wlezl's algorithm) looks doable. And I think this is all you need to determine which set of points is more likely to belong to the smaller circle.