At the top of the Kailash Blades website, click on the "Options" tab, sheaths are the first item discussed:
kailashblades.com
Basically, the Salyani sheath leather is more involved and labor intensive, and has a mottled texture. The sheath itself is also more ornate. Check out the Salyani khukuri, there's a picture of the sheath. Their gallery and Instagram pics show even better details.
What surprised me about the Salyani sheath is that it says it's thinner leather and suggests using it more for display, and/or ordering a modern (more durable?) sheath for carry.
I'm sure Andrew will answer and give qualified, experienced advice when he sees this thread.
For my orders, I've opted for either traditional or military daps for display purposes (depending on the default options) and added either kydex or western leather sheaths for actual field use.
Edit: The only "Raw" that I remember seeing is under the blade finish options, I'm not sure what you mean by raw leather. The raw blade finish is like a forge finish in western terms: black with forging scale and hammer marks. In those terms, I like it very much and was tempted to get that on my Ek Chirra and Mini.