Comparing both class definitions we can observe the following:
Both classes have two data elements x and y. In the class Point these elements describe the position of the point, in the case of class Circle they describe the circle's center. Thus, x and y have the same meaning in both classes: They describe the position of their associated object by defining a point.
Both classes offer the same set of methods to get and set the value of the two data elements x and y.
Class Circle ``adds'' a new data element radius and corresponding access methods.