Pertaining to the actual formula...
The circumference and area of a circle both need the radius (or diameter, one to find the other) and pi to be solved.
However, the area of a circle squares the radius while the circumference doubles it. They then both multiply pi.
Pertaining to the actual definition...
Both the circumference and area measure a part of the circle.
However, the circumference measures the distance around the circle while the area measured the space inside the circle.
Hope this helps!