You're using concave curves on soft parts of the pony. The show doesn't do that. Only use convex curves on soft tissue like pony fur and skin. Look at the pony's snout, it curves inwards, it really should have a very gentle outward curve.
It's a basic animation trick, once you start noticing it (like the blue/orange contrast) you'll see it everywhere. Only use concave lines when you want something to look sharp, artificial or otherworldly, never on creatures. Unless you're making an eXtrme artstyle. Like Loonatics. Which My Little Pony most definitely isn't. Even the unicorn horns curve outwards, even if they're supposed to be hard. It's really only beaks and claws you can do concave curves on, since they're supposed to be sharp.