Are you sure they aren't just different species, that grow ball form vs branching. Mine is ball form and while it eats plenty of pellets and flakes by default, I have never spot fed. In about 3yrs it's gone from 1 head to about 50(guestimate) and is a little bigger than a softball.
It's all speculation, I am pretty sure they were all the same species but this particular coral gets very little food as it is in a tank without fish.