The main difference is their diet. Animals that eat only meat are carnivores. When animals eat both plants and meat, they are called omnivores.
1. Teeth
Carnivore's teeth are long, sharp and pointed, helpful piercing into flesh. Omnivore's (meat and plant eaters) teeth are similar to that of carnivores. Omnivores have sharp canine teeth at the front of the mouth to cater for meat, and flat molars to allow a grinding action for plant material.
2. Digestive enzymes
As with the herbivore, amylase is contained within the saliva of the omnivore, which also utilises the chewing action to help break down the coarse fibres and carbohydrates that makes up plant material. Amylase is not present within the saliva of carnivores hence the burden of digesting carbohydrates is taken by the pancreas. Long term over loading of the pancreas is associated with insulin resistance and ultimately the failure of the pancreas to produce of insulin as found in type II diabetes.
3. Jaws
The jaws of carnivores are highly muscular and strong, which ensure a firm grip on the captured prey. They have stronger jaws than omnivores.
4. Gut
Usually, the gut of the herbivores is longer than in carnivores, but omnivores have a long gut to capacitate both types of diets. Carnivores gut is not as long as the herbivores and omnivores. Therefore, they get hungry and thirsty more often than herbivores.