If your 'cannonball' has a wick, it is a grenade if small enough to fit in a hand, or if large enough a mortar bomb to be fired from a specialised cannon. A cannonball is solid and it hurts what it hits, it is basically a large bullet. It is used against ships and buildings and only against people if shooting beyond range of any other weapon. A mortar bomb travels a set distance and then explodes scattering the fragments of the bomb over a large area, it is less effective against structures, but causes massive casualties.
If your 'cannonball' has a wick, it is a grenade if small enough to fit in a hand, or if large enough a mortar bomb to be fired from a specialised cannon. A cannonball is solid and it hurts what it hits, it is basically a large bullet. It is used against ships and buildings and only against people if shooting beyond range of any other weapon. A mortar bomb travels a set distance and then explodes scattering the fragments of the bomb over a large area, it is less effective against structures, but causes massive casualties.