Question

If the force exerted by a canon on a cannonball is equal to the force exerted by a cannonball on a canon why does the cannonball move so much farther than the canon?

Answer 1

That is because of the mass of the object. Even though equal forces are being exerted, the cannonball moves farther at a faster rate because of the mass. 

Answer 2

For exactly the same reason that, when you jump up, your force
against the Earth is equal to the Earth's force on you, but you
move so much farther than the Earth moves.

In a collision, canon-shot, rifle-shot, jump, tennis serve, golf shot,
or home-run, the forces are equal in both directions, but the effect
is greater on the smaller mass, and smaller on the greater mass.