A radius is a line that extends from a point to the circumference of a circle. A chamfer is the part of an edge or surface that forms an angle with the plane on which it lies.
Radius: The distance from any point on one side of the circle to the same point on the other side.
Chamfer: The amount of material removed from an edge or surface, such as at an angle, to create an edge or surface with a more gradual slope.