This is going to sound like a weird answer at first. Dogs are one of the weirdest animals when you think about how different all the breeds are. It ranges from a 5lb teacup poodle to a Mastiff that can be over 200lb. There is no other animal that is the same breed but is so different in the way they look. Man would selectively breed dogs for a purpose and we ended up with dogs that are so drastically different. You see two different breeds of dogs together and sometimes it’s hard to think they are even the same animal they are so different.