The difference between the spells? Mo rolled his seed between his fingers and considered what might be the difference. He liked Benjy's answer, honestly, where the amount of concentration and effort in the more advanced spell suggested some differing long term effect.

Benjy was super smart.

Mo raised his hand. "Professor, could it be that the Vitaris Charm merely accelerates the plant through the life cycle, so while it grows more quickly it also dies sooner? And the Herbivicus Charm... maybe it actually grows the plant without shortening the life cycle of the plant?" Or some variant of those thoughts.