Hoof footsteps on rock.
Bob their heads when they run.
Have "Head is Pounding" instead of "Head is Pounding, Hands are Shaking" (except Pinkie)
Won't lose sanity in darkness (except Fluttershy)
Pony step sounds up ladder are faster.
Have less mass than Daniel.
Enemies won't glow in the dark (except Rarity)
Pony version (faster sounds) of climbing up ladders.