A Herbivore: Eats only plants
A Carnivore: Eats only meat
An Omnivore: Eats both
Knowing this:
Buffalo - Herbivore (eat only plants)
Bear- Omnivore (eats meat and plants, like fish and berries)
Spider - Carnivore (most spider species eat other insects)
Cow- Herbivore (mainly eats plants)