On the surface, at first glance, there may not seem like much of a difference between otters and beavers. Yet they are vastly different animals, and even come from different orders.
The otter is a member of the order Carnivora. The beaver is a member of the order Rodentia. This is based on some physical differences, but also highlights a main difference in their lifestyle. The otter is a carnivore, while the dam-building beaver is a rodent, and prefers the vegetarian lifestyle.
The otter is a relative of the weasel. The beaver is a relative of the rat. While they maintain very similar characteristics, their overall origin differences create different types of behaviors, and different characteristics of study.