Of coarse the 15fps is going to look choppy, that's a given. But the other two, it's just one bouncing square so yeah, it looks a little more fluid (I've seen it before). Get 10 bouncing squares and you'll notice no difference. It's more than just fps. It's also refresh rate, and how it's being delivered and by what means. So yeah (rolls eyes), whatever!
You also must be running an 4 year old nvidia GPU in your PC because the difference is so subtle to me that it makes no difference. But I guess phone gaming is a totally different beast. One that I really could careless about.