Question

what is radius of a circle and what is circumference

Answer 1

the line joining the centre of the circle and it's circumference is called radius
and circumference is the perimeter of circle

Answer 2

${\huge{\red{Hi\:Mate}}}$

The circumference is the outside perimeter of a circle. It's the distance around a circle. A radius can be a line from any point on the circumference to the center of the circle. 

The distance around the edge of a circle (or any curvy shape). It is a type of perimeter.