Which of these animal groups eats only plants or their products?

Animals are classified into different groups based on their food habits. 

The group of animals that eats only plants or their products to derive nutrition and energy is called herbivores. A few examples of herbivores are cows, buffaloes, goats, grasshoppers,  etc. 

Animals that eat other animals are called carnivores. For e.g., tigers, lions, foxes, eagles, etc. 

Omnivores are those animals that eat both plants and animals. For e.g., crows, bears, human beings, etc.