We cannot speak to the Ninja as this is not our product.
However, comparing the Magic Bullet vs. The NutriBullet - The NutriBullet has a larger capacity, over twice the power and a completely different blade design than the Magic Bullet. The NutriBullet is specifically designed to pulverize and emulsify foods including fruit skins, seeds, stems, vegetables, nuts and tough root vegetables (like ginger and beets), while retaining all of the fiber and nutrients.
The Magic Bullet is a smaller, less powerful blending solution for making iced coffee drinks, fruit smoothies, sorbets or milk shakes as well as chopping onion or mincing garlic and other day-to-day kitchen uses.