Shelties are pretty easy. You basically have three coat colours: sable, bi-black, and tri.
The sable is the brown/tan colour. There's a range of names that people have created to try and describe the different levels of sable, like golden sable (more yellow-y), red sable (like Auggie's coat is pretty reddish), and shaded sable (lots of black) but sable is pretty much sable.
A bi-black is just black and white, no brown.
The tri is black, white, and brown.
On all of these you can have the merling which gives you a sable merle, bi-blue, and blue merle respectively.
The colour-headed white is a dog that is so heavily white factored they basically have no colouring anywhere but on their head.
And then of course there's the double merle in shelties as well.