What are 'Range' and 'Radius' queries and what is the difference between them?
Range stands for one-dimensional distance while radius is standing for two-dimensional one.

Let's the data is the timestamp. It is one-dimensional and you can define part of data "in range" or timestamp BETWEEN a AND b. If your data represents the plane of points x:y then you can define part of them as "points closer than radius Z to the given point" or (x-x1)^2 + (y-y1)^2 &lt; Z^2.