Pony Comparison - Headcanon

This is just a little something I whipped up for the sake of me being able to ramble about my headcanons and I sort of don't want to forget anything so this seemed like a good idea. And whilst these points in the headcanon won't change, the art style will just a little bit to make every pony shorter. I prefer the look over the more horse-ish appearance with the long legs which I was just experimenting with. They're be more like '.:Serene:.' AJ style.
Anyway, I believe that these three; Applejack, Rainbow Dash and pre-alicorn Twilight, will pretty much be the embodiments of my headcanon for each pony tribe so that's why I used them, not for any other reason.

So, onto the headcanon!

Earth ponies are both the tallest and the broadest of the tribes. They're naturally well muscled. Applejack is almost an extreme because part of my headcanon for her is that her dad was a really big stallion, taller than even Macintosh when full grown which... doesn't actually help much because I don't have an image but he is considerably taller than AJ and her brother. This means that AJ is really tall. She can loom over plenty of stallions just fine which is just perfect for looking down her nose at the cocky ones. Earth ponies also have a thicker coat, broader hooves and longer feathers (apparently that is the name of the fluff around their hooves. I know, I was confused too), leaving them looking more akin to Shire horses and making them far more resistant to the elements and perfect for the farming work that many revert to. Their magic is constant, subtle and is far harder to tap into. It influences the nature they interact with to flourish and grow and makes their bones and muscles denser. My Apple family headcanon is that they all have an excess of this magic, aiding their success.
So yeah, earth ponies. The biggest, strongest and most resilient of the tribes.

Pegasus ponies are the opposite to earth ponies in many aspects. Firstly, I'd believe them to have hollow bones, much like birds which make them lighter and so makes flight easier for them. It's also useful for when they crash. Rainbow Dash, as a high speed flier, has more than her fair share of crashes. Birds, when they break their legs, can take as little as 2 weeks to heal whereas a human would take at least 6. With the aid of magic, I'd think that any Pegasus, even with the nastiest of breaks, could be up in the air a week later with no long lasting side effects. Pegasus ponies are also quite tall and toned. The long legs and the muscle allow for a more powerful, and fast, take off. Rainbow would be a prime example of this with her standing level, and above, plenty of ponies. Except AJ and Mac and she is quietly disgruntled by that. They have shorter hoof feathers and smaller hooves than earth ponies. They're a little more... dainty. Their magic does a lot of things, helping them resist G-forces in flight, interact with clouds and giving their coats a level of insulation, preventing serious damage when electrocuted, a common enough occurrence for weather pegasus ponies. It's mostly innate but some can tap into it more readily, such as Rainbow Dash, which makes weather work and flight a lot simpler.
To summarise; they're lean, tall and light. Usually. Roid Rage is an exception.

Unicorns have the smallest frames of all the tribes but have heads the same size as a Pegasus', maybe slightly bigger, with thicker neck too. This is because of the added weight of their horns and the pressure that magical casting can place upon them. Think, the recoil of a gun. So, though they're the smallest, if a Unicorn decided to headbutt you, you'd probably feel it like it was an Earth pony blow. They have less muscle in their legs yet more in the backs, once again as support for magical casting. They also have really short feathers and the smallest hooves. The smaller overall build makes transportation spells, such as teleportation, easier, with less mass to carry. Hence why Twilight seems to have next to no difficulty. She is a small unicorn. She's light, with strong neck muscles that make casting far simpler. In the above image, she only looks annoyed because in this headcanon, she's very aware of how tiny she is, especially in comparison to AJ who practically dwarfs her. Anyway, it is part of my headcanon that unicorn magic isn't really there all the time. This is kind of supported by how baffled Twi was in EqG when she realised she couldn't do magic. This, indicates to me, that it isn't a heavy presence and more or less is something that can be drawn in from the outside world and converted into something usable through the use of spells. It's the strongest magic but non-constant and the most complex.
So, that's unicorns; they're small and light with Pegasus' sized heads and well muscled necks.
On a side note, I think Twilight would grow to around the same height as RD after her alicorn transformation. She would be very pleased about that fact and RD would be very disappointed that she couldn't pick on Twi any more.

I've put way too much though into this, haven't I?... Yeah, I thought so. Feel free to question me though and point out the flaws in my headcanon. I'd love to hear opinions on it.