Explain the circumference and area of circle ? 

Circumference of a circle is the length of boundary around the circle.

It is expressed in the formula as,

Circumference of circle with radius 'r' $= 2πr$. 

Area of the circle is the amount of space inside the boundary of the circle.

It is expressed in the formula as,

 Area of circle with radius 'r' $= πr^2$. 

For example, let us consider the following figure.

In the above figure, 

The length of blue colored line outside the circle is the circumference of the circle.

The region of yellow colored surface inside the blue colored line is the area of the circle.