Well along with Earth ponies and unicorns, the third main species of pony are pegasi and they're in charge of the weather. Here, ponies have to make the weather work, the plants grow, and the seasons come, they don't come naturally like in the human world. Then there are alicorns, they are a combination of the three pony species and maintain princess status. They're the rulers of Equestria and have a specific task to tend to, such as rising the sun. Then we also have animals that you would find in the human world like turtles and owls, but the vast majority can't talk.